Systems and methods for sensing using consumer electronic devices

ABSTRACT

Embodiments described herein generally relate to: sensing and/or authentication using luminescence imaging; diagnostic assays, systems, and related methods; temporal thermal sensing and related methods; and/or to emissive species, such as those excitable by white light, and related systems and methods.

RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119(e) to U.S.Provisional Patent Application No. 63/085,929, filed Sep. 30, 2020,entitled “WHITE LIGHT EMISSIVE SPECIES AND RELATED METHODS,” to U.S.Provisional Patent Application No. 63/069,544, filed Aug. 24, 2020,entitled “DIAGNOSTIC ASSAYS AND RELATED METHODS,” to U.S. ProvisionalPatent Application No. 63/054,176, filed Jul. 20, 2020, entitled“TEMPORAL THERMAL SENSING AND RELATED METHODS,” and to U.S. ProvisionalPatent Application No. 62/916,331, filed Oct. 17, 2019, entitled“LUMINESCENCE IMAGING FOR SENSING AND/OR AUTHENTICATION,” the contentsof each of which are hereby incorporated by reference in their entiretyfor all purposes.

FIELD

Embodiments described herein generally relate to: sensing and/orauthentication using luminescence imaging; diagnostic assays, systems,and related methods; temporal thermal sensing and related methods;and/or to emissive species, such as those excitable by white light, andrelated systems and methods.

BACKGROUND

Sensing technology is being used in a wide variety of applications suchas safety, security, process monitoring, and air quality control.However, many sensors are limited by complex manufacturing processes,low sensitivity, and/or false indications of detection. As such, theapplications of such sensors are often limited.

Many products can be damaged when exposed to temperatures above or belowa threshold level for a period of time. Products at risk of degradationinclude biological materials, tissue, medicines, food, beverages,electronics, live cells, organs, livestock, and the like. It is oftenthe case that it is not simply the peak temperature that is mostimportant, but may also include the time spent at a given temperature.For example, a short time at a higher temperature can cause similardegradation to a product as a longer time at a lower temperatureexceeding a threshold value. In simple terms the product of thetemperature and time is an important metric. Materials and methodscapable of providing this information may include time temperatureindicators (TTI) and/or dosimetric labels when applied to packaging. Forexample, thermally activated color changes in a dosimeter label are oneway to monitor such changes. However, these methods have limited utilityand new methods that provide more information which can be readilycaptured by readers and greater precision are needed.

Molecular and biological diagnostic tests generally leveraging thelow-cost nature and ubiquity of lateral flow assays as well as verticalflow assays and genetic assays based on biological components such asantigens, antibodies, and nucleotides are critical to ensuring publichealth and safety. Although these assays are easy to use, they aretypically analyzed visually using the human eye which injects a highdegree of variability and/or subjectivity into the data interpretation.To address this shortcoming, new approaches employing automation andmachine vision are necessary to improve the sensitivity and accuracy oflateral flow assays. Although smartphones have recently been used toprovide high-resolution image acquisition and analysis, these methodsare still limited.

Accordingly, improved methods and systems are needed.

SUMMARY

Articles, systems, and methods for luminescence imaging for sensingand/or authentication are generally disclosed.

In some aspects, an imaging device is provided. In some embodiments, theimaging device comprises a source of electromagnetic radiationconfigured to emit radiation to excite non-steady-state emission inemissive species during emission time periods (e.g., emission lifetime)of the emissive species. In some embodiments, the emission time periodis at least 10 nanoseconds. In some embodiments, an electromagneticradiation sensor comprising a plurality of photodetectors is arranged inan array of rows and columns, wherein the electromagnetic radiationsensor is configured to sense the non-steady-state emission from theemissive species during the emission time period and processingcircuitry configured to sequentially read out rows or columns of thearray to provide a plurality of time-encoded signals and identify acharacteristic of the emissive species based on a comparison of at leasttwo of the plurality of time-encoded signals.

In some embodiments, the imaging device comprises a source ofelectromagnetic radiation configured to emit radiation to excitenon-steady-state emission in emissive species during emission timeperiods of the emissive species, the emission time periods being atleast 10 nanoseconds, an electromagnetic radiation sensor comprising aplurality of photodetectors arranged in an array of rows and columns,wherein the electromagnetic radiation sensor is configured to sense thenon-steady-state emission from the emissive species during the emissiontime period and processing circuitry configured to globally exposeand/or read data from the electromagnetic radiation sensor to provide aplurality of time-encoded signals and identify a characteristic of theemissive species based on a comparison of two or more of the pluralityof time-encoded signals.

In some embodiments, the processing circuitry is further configured togenerate one or more images based on the plurality of time-encodedsignals, and wherein identifying the characteristic of the emissivespecies is based on the one or more images.

In some aspects, a system is provided. In some embodiments, the systemcomprises an excitation component configured to excite an emissivespecies such that the emissive species produces a detectablenon-steady-state emission during an emission time period. In someembodiments, the emission time period is at least 10 nanoseconds. Insome embodiments, the system comprises an image sensor configured todetect at least a portion of the detectable non-steady-state emission.In some embodiments, the system comprises an electronic hardwarecomponent configured to produce a single image comprising a firstportion corresponding to a first portion of the emission time period anda second portion corresponding to a second portion of the emission timeperiod.

In some embodiments, the system comprises an excitation componentconfigured to expose an emissive species to non-steady-stateelectromagnetic radiation. In some embodiments, the system comprises animage sensor configured to detect at least a portion of electromagneticradiation emitted by the emissive species. In some embodiments, thesystem comprises an electronic hardware component configured to producea single image comprising at least a first image portion correspondingto emission of electromagnetic radiation by the emissive species atleast at a first point in time, and a second image portion correspondingto emission of electromagnetic radiation by the emissive species atleast at a second point in time.

In some embodiments, a system configured for identification of acharacteristic of an article is provided. In some embodiments, thesystem comprises a chemical tag associated with the article. In someembodiments, the chemical tag comprises an emissive species. In someembodiments, the emissive species produces a detectable non-steady-stateemission during an emission time period under a set of conditions. Insome embodiments, the emission time period is at least 10 nanoseconds.In some embodiments, the system comprises an excitation componentconfigured to excite the emissive species under the set of conditionssuch that the detectable non-steady-state emission, which varies overthe image capture time period, is produced. In some embodiments, thesystem comprises an image sensor configured to detect the detectableemission. In some embodiments, the system comprises an electronichardware component configured to convert the detectable emission into asingle image. In some embodiments, the single image comprises a firstportion corresponding to a first portion of the emission time period anda second portion corresponding to a second portion of the emission timeperiod. In some embodiments, a difference between a property of thefirst portion and the second portion is associated with a characteristicof the article.

In some embodiments, a system configured for identification of acharacteristic of an article is provided. In some embodiments, thesystem comprises a chemical tag associated with the article. In someembodiments, the chemical tag comprises an emissive species. In someembodiments, the chemical tag produces a detectable non-steady-stateemission during an emission time period under a set of conditions. Insome embodiments, the emission time period is at least 10 nanoseconds.In some embodiments, the system comprises an excitation componentconfigured to excite the emissive species under the set of conditionssuch that the detectable non-steady-state emission, which varies overthe data/image capture time-period, is produced. In some embodiments,the system comprises an image sensor configured to detect the detectablenon-steady-state emission. In some embodiments, the system comprises anelectronic hardware component configured to convert the detectedemission into a single image. In some embodiments, the single imagecomprises a first portion corresponding to a first portion of theemission time period and a second portion corresponding to a secondportion of the emission time period. In some embodiments, a differencebetween a property of the first portion and the second portion isassociated with a characteristic of the article.

In some embodiments, a system configured for identification of acharacteristic of a chemical tag is provided. In some embodiments, thesystem comprises a chemical tag. In some embodiments, the chemical tagproduces a detectable emission during an emission time period under aset of conditions. In some embodiments, the emission time period is atleast 10 nanoseconds. In some embodiments, the system comprises anexcitation component configured to excite the chemical tag under the setof conditions such that the detectable emission is produced. In someembodiments, the system comprises an image sensor configured to detectthe detectable photon emission. In some embodiments, the systemcomprises an electronic hardware component configured to convert thedetected emission into a single image. In some embodiments, the singleimage comprises a first portion corresponding to a first portion of theemission time period and a second portion corresponding to a secondportion of the emission time period. In some embodiments, a differencebetween a property of the first portion and the second portion isassociated with a characteristic of the chemical tag.

In some embodiments, a system comprises a radiation source configured togenerate electromagnetic radiation for exciting an emissive species suchthat the emissive species produces a detectable non-steady-stateemission during an emission time period, the emission time period beingat least 10 nanoseconds, a sensor configured to detect, during a firstportion of the emission time period, a first emission from the emissivespecies, and detect, during a second portion of the emission timeperiod, a second emission from the emissive species, and processingcircuitry configured to identify a characteristic of the emissivespecies based on a difference between a property of the first emissiondetected during the first portion of the emission time period and aproperty of the second emission detected during the second portion ofthe emission time period.

In some embodiments, the system comprises a radiation source configuredto generate electromagnetic radiation for exciting an emissive speciessuch that the emissive species produces a detectable non-steady-stateemission during an emission time period, an electromagnetic radiationsensor configured to sense during a single exposure: first emission fromthe emissive species during a first portion of the emission time period,and second emission from the emissive species during a second portion ofthe emission time period, wherein the emission time period is at least10 nanoseconds and is less than a duration of the single exposure andprocessing circuitry configured to identify a characteristic of theemissive species based on a difference between a property of the firstemissions detected during the first portion of the emission time periodand a property of the second emissions detected during the secondportion of the emission time period.

In some aspects, a method for identifying a change in an emissivespecies over a period of time is provided. In some embodiments, themethod comprises exciting the species such that it produces a detectablenon-steady-state emission during an emission time period. In someembodiments, the excited state emission lifetime (e.g., the emissiontime period) of one or more of the emissive species is at least 10 ns.In some embodiments, the method comprises obtaining, using an imagesensor, capable of collecting photon emission data, a single image ofwhich has at least a portion of the detectable non-steady-state photonemission. In some embodiments, a first portion of the single imagecorresponds to a first portion of the emission time period. In someembodiments, a second portion of the single image corresponds to asecond portion of the emission time period. In some embodiments, themethod comprises determining, based upon a difference between the firstportion and the second portion of the single image, the change in thespecies.

In some embodiments, a first portion of the single image corresponds toa steady-state emission. In some embodiments, a second portion of thesingle image corresponds to a non-steady-state emission. In someembodiments, the method comprises determining, based upon a differencebetween the steady-state and non-steady-state emission, a characteristicand/or change in the species. In some embodiments, the method comprisesdetermining the difference between multiple non-steady-state emissions.In some embodiments, the method comprises determining the differencebetween multiple steady-state and non-steady-state emissions.

In some embodiments, a method for identifying a change in an emissivespecies over a period of time is provided. In some embodiments, themethod comprises causing the species to emit such that anon-steady-state photon emission is detectable during an emission timeperiod. In some embodiments, the method comprises obtaining, using animage sensor, a single image of at least a portion of theelectromagnetic radiation emitted by the emissive species. In someembodiments, the method comprises identifying information from a firstimage portion corresponding to emission of electromagnetic radiation bythe emissive species at least at a first point in time. In someembodiments, the method comprises identifying information from a secondimage portion corresponding to emission of electromagnetic radiation bythe emissive species at least at a second point in time. In someembodiments, the method comprises determining, from at least theinformation from the first image portion and the information from thesecond image portion, the change in the emissive species.

In some embodiments, a method for identifying a characteristic of anemissive species is provided. In some embodiments, the method comprisesexciting the species such that the species produces a detectablenon-steady-state emission during an emission time period. In someembodiments, the emission time period is at least 10 nanoseconds. Insome embodiments, the method comprises obtaining, using an image sensor,a first image of the detectable non-steady-state emission. In someembodiments, a first portion of the first image corresponds to a firstportion of the emission time period. In some embodiments, a secondportion of the first image corresponds to a second portion of theemission time period. In some embodiments, the method comprisesdetermining, based upon a difference between the first portion and thesecond portion of the first image, the characteristic of the species.

In some embodiments, a method for identifying a characteristic of anarticle is provided. In some embodiments, the method comprisespositioning an image sensor proximate an article suspected of containingan emissive tag. In some embodiments, the method comprises stimulatingthe article such that the emissive tag, if present, produces adetectable non-steady-state emission. In some embodiments, the methodcomprises obtaining, using the image sensor, a single image of thedetectable non-steady-state emission. In some embodiments, the methodcomprises adding a sample of the article to be analyzed to a secondarticle, and then analyzing the second article with an image sensor. Insome embodiments, a first portion of the single image corresponds to afirst time period after stimulating the analyte. In some embodiments, asecond portion of the single image corresponds to a second time periodafter stimulating the analyte, different than the first time period. Insome embodiments, the method comprises determining, based upon adifference between the first portion and the second portion of thesingle image, the characteristic of the article.

In some embodiments, the method comprises generating electromagneticradiation, exciting, using the electromagnetic radiation, an emissivespecies such that the emissive species produces a detectablenon-steady-state emission during an emission time period, the emissiontime period being at least 10 nanoseconds, detecting, during a firstportion of the emission time period, a first emission from the emissivespecies, and detecting, during a second portion of the emission timeperiod, a second emission from the emissive species, and identifying thecharacteristic of the emissive species based on a difference between aproperty of the first emission detected during the first portion of theemission time period and a property of the second emission detectedduring the second portion of the emission time period.

In some embodiments, a method for detecting the presence of a stimulusis provided. In some embodiments, the method comprises exposing anarticle comprising a chemical tag to a set of conditions comprising thestimulus. In some embodiments, the chemical tag undergoes a chemicaland/or biological reaction and/or association in the presence of thestimulus that changes the lifetime, wavelength, and/or intensity of oneor more emissive species in the tag. In some embodiments, the methodcomprises positioning an image sensor proximate the article. In someembodiments, the method comprises obtaining, using the image sensor, asingle image of a portion of the article comprising the chemical tag. Insome embodiments, a first portion of the single image corresponds to afirst time period after exposing the article. In some embodiments, asecond portion of the single image corresponds to a second time periodafter exposing the article, different than the first time period. Insome embodiments, the method comprises determining, based upon adifference between the first portion and the second portion of thesingle image, the characteristic of the article. In some embodiments,the method comprises determining, based upon a difference between asteady-state and non-steady-state photon emission, the characteristic ofthe article. In some embodiments, the method comprises determining,based upon a difference between different non-steady-state photonemissions, the characteristic of the article. In some embodiments asingle image can be composed of emitted light from both steady-state andnon-steady-state photon emission. In some embodiments, the method may beextended to obtain and use information from additional portions of theimages at multiple points in time. In some embodiments, the portions areanalyzed with plane or circularly polarized light, different wavelengthsof light, or other non-steady-state electromagnetic radiation.

Components, systems, and methods for temporal thermal sensing are alsogenerally disclosed.

In one aspect, compositions are provided. In some embodiments, thecomposition comprises an emissive species configured to be associatedwith an article, wherein excitation of the emissive species produces adetectable signal having one or more delayed emissions of greater thanor equal to 10 nanoseconds, and wherein the detectable signalcorresponds to a temporal thermal history of the article.

In another aspect, labels are provided. In some embodiments, the labelcomprises a first emissive species optionally having one or more firstdetectable delayed emission(s) from emissive species having excitedstate lifetimes greater than or equal to 10 nanoseconds corresponding toa first temporal thermal history of the first emissive species andoptionally a second emissive species having one or more seconddetectable delayed emission(s) from emissive species having excitedstate lifetimes greater than or equal to 10 nanoseconds corresponding toa second temporal thermal history of the second emissive species,different than the first temporal thermal history. The first detectabledelayed emission, if present upon excitation of the first emissivespecies, corresponds to identification of the first emissive speciesbeing exposed to the first temporal thermal history and the seconddetectable delayed emission, if detectable, corresponds toidentification of the second emissive species being exposed to thesecond temporal thermal history. The first emissive species in someembodiments, transforms into the second emissive species as a result ofa particular temporal thermal history. In some embodiments, multipleemissive species may change to provide additional information about anarticle's temporal thermal history. In some embodiments, one or moreemissive species may provide information about a temporal thermalhistory (e.g., of an article, of the emissive species).

In another aspect, methods are provided. In some embodiments, the methodcomprises exciting one or more emissive species associated with anarticle and detecting, using a detector, a detectable delayed emissionof the emissive species, wherein the detectable delayed emission, ifpresent, has a delayed emission with an excited state lifetime greaterthan or equal to 10 nanoseconds, and wherein the detectable delayedemission, if present, corresponds to an exposure of the article to atemporal thermal history.

In some embodiments, the method comprises exciting one or more firstemissive species, optionally, exciting one or more second emissivespecies, detecting, using a detector, a first detectable delayedemission(s) produced by the first emissive species and/or a seconddetectable delayed emission(s) produced by the second emissive species,wherein, the first detectable delayed emission, if present, correspondsto exposure of the first emissive species to a first temperature, andwherein, the second detectable delayed emission, if present, correspondsto exposure of the second emissive species to a second temperature,different than the first temperature, wherein, at least one detectabledelayed emission is present.

In some embodiments, the system comprises an excitation componentconfigured to excite, using electromagnetic radiation, an emissivespecies such that, if single or multiple emissive species, or theirprecursors, were exposed to a temporal thermal history, produces adetectable delayed emission with an excited state lifetime greater thanor equal to 10 nanoseconds and a detector configured to detect at leasta portion of the detectable delayed emission.

In some embodiments, the system comprises a radiation source configuredto generate electromagnetic radiation for exciting an emissive speciessuch that the emissive species produces a detectable non-steady-stateemission during an emission time period, an electromagnetic radiationsensor including a plurality of photodetectors configured to detect thenon-steady state emission during the emission time period; a controllerconfigured to control a timing of generation of the electromagneticradiation by the radiation source such that pulsed or frequencymodulated intensity electromagnetic radiation is generated during thecapture of the one or more images, and processing circuitry configuredto generate, based on output of the plurality of photodetectors, one ormore images, the emission time period being less than a time to capturea single image of the one or more images and for each of the one or moreimages, determine a first property of a first portion of the image and asecond property of a second portion of the image, and identify acharacteristic of the emissive species based, at least in part, on thefirst property and the second property.

Diagnostic assays and related methods are also generally disclosed.

In one aspect, methods are provided. In some embodiments, the methodcomprises determining an identity or characteristic of achemical/biological species by combining a first electromagneticradiation signal comprising at least a steady-state photon emissionevent, and a second electromagnetic radiation signal comprising at leasta non-steady-state photon emission event. In some embodiments, themethod comprises determining an identity or characteristic of achemical/biological species by combining a first electromagneticradiation signal and a second electromagnetic radiation signal, whereinthe first electromagnetic signal comprises at least a first photonemission event from an emissive species with an excited state lifetimeless than 10 nanoseconds. In some embodiments, the first photon emissionevent is detected under steady-steady state conditions. A secondelectromagnetic signal comprising at least a second photon emissionevent from an emissive species with an excited state lifetime of atleast 10 nanoseconds is detected, in some embodiments, undernon-steady-state conditions. In some embodiments, data (e.g., datauseful for generating an image) and/or an image is collected after anon-steady-state pulsed emission and only a non-steady-state photonemission is detected. In some embodiments, an image is generated overthe time period wherein one or more portions of the image are obtainedwith a steady-state excitation to detect a steady-state photon emissionand one or more portions of the image are obtained after the excitationis removed to enable the detection of a non-steady-state photonemission.

In some embodiments, the first photon emission event comprises anemission produced by an emissive species having an excited statelifetime of less than or equal to 10 nanoseconds.

In some embodiments, the second photon emission event comprises anemission produced by an emissive species having an excited statelifetime of at least 10 nanoseconds.

In some embodiments, the method comprises detecting two or more signalsemanating from the assay, wherein each of the two or more signals areselected from a subtractive color, reflected color, scattering,chemiluminescence, prompt-fluorescence, delayed-fluorescence,prompt-phosphorescence, and delayed-phosphorescence emission. In someembodiments, each signal is read using a smartphone or digital camera.

In another aspect, systems are provided. In some embodiments, the systemcomprises an excitation component configured to excite a first emissivespecies such that the first emissive species produces a detectablesteady-state photon emission, the excitation component is configured toexcite a second emissive species such that the second emissive speciesproduces a detectable non-steady-state photon emission, and a sensorconfigured to detect at least a portion of the detectable steady-statephoton emission and at least a portion of the detectablenon-steady-state emission.

In some embodiments, the system comprises an electronic hardwarecomponent configured to combine the detectable steady-state emission andthe detectable non-steady-state emission into a determinable signal.

In some embodiments, the detectable steady-state emission and/or thedetectable non-steady-state emission correspond to a characteristic ofthe first emissive species and/or the second emissive species,respectively.

Emissive species, such as those excitable by white light, and relatedsystems and methods are also generally disclosed.

In one aspect, systems are provided. In some embodiments, the systemcomprises a source of an electromagnetic radiation spectrum and anemissive species, wherein a first portion of the electromagneticradiation spectrum comprises a wavelength of between 425 nm and 475 nm,wherein a second portion of the electromagnetic radiation spectrumcomprises a wavelength of between 525 nm and 725 nm, and wherein thesource produces a wavelength of electromagnetic radiation that interactswith the emissive species such that the emissive species produces adetectable signal having one or more delayed emissions from emissivespecies having excited state lifetimes greater than or equal to 10nanoseconds.

In some embodiments, the system comprises a source of a plurality ofwavelengths of electromagnetic radiation and an emissive species,wherein the emissive species produces a detectable signal having one ormore delayed emissions of greater than or equal to 10 nanoseconds, andwherein the plurality of wavelengths of electromagnetic radiationgenerated by the source spans greater than or equal to 50 nm.

In some embodiments, the system comprises a source of electromagneticradiation associated with a consumer electronic device, a sensorassociated with the consumer electronic device, and an emissive speciescapable of producing a detectable signal by the sensor, the detectablesignal having one or more delayed emissions from an emissive specieshaving an excited state lifetime greater than or equal to 10nanoseconds.

In some embodiments, the electromagnetic radiation produced by thesource is unadulterated prior to exposure to the emissive species. Insome embodiments, the system does not comprise a light filter positionedbetween the source and the emissive species.

In some embodiments, the source is a component of a consumer electronicdevice. In some embodiments, the consumer electronic device is asmartphone, tablet, computer, digital camera, or the like.

In some embodiments, the system comprises an excitation componentconfigured to produce a plurality of wavelengths of electromagneticradiation, wherein the excitation component is configured to excite afirst emissive species such that the first emissive species produces adetectable stead-state photon emission signal, the excitation componentis configured to excite a second emissive species such that the secondemissive species produces a detectable non-steady-state photon emissionsignal, and a sensor configured to detect at least a portion of thedetectable steady-state photon emission signal and at least a portion ofthe detectable non-steady-state emission signal.

In some embodiments, the system comprises a radiation source configuredto generate a plurality of wavelengths of electromagnetic radiation forexciting an emissive species such that the emissive species produces adetectable non-steady-state emission during an emission time period, theexcited state lifetime of the emissive species being least 10nanoseconds, a sensor configured to detect, during a first portion ofthe emission time period, a first emission from the emissive species,and detect, during a second portion of the emission time period, asecond emission from the emissive species, and processing circuitrycapable of identifying a characteristic of the emissive species based ona difference between a property of the first emission detected duringthe first portion of the emission time period and a property of thesecond emission detected during the second portion of the emission timeperiod.

In another aspect, methods are provided. In some embodiments, the methodcomprises using a consumer electronic device to determine an identity orcharacteristic of a chemical/biological species, wherein the consumerelectronic device comprises a source of a spectrum of electromagneticradiation and exposing an emissive species to the spectrum ofelectromagnetic radiation such that the emissive species produces adetectable emission which corresponds to the identity or characteristicof the chemical/biological species and which is detectable by theconsumer electronic device.

In some embodiments, the method comprises determining an identity orcharacteristic of a chemical/biological species by exposing an emissivespecies to an electromagnetic radiation spectrum generated by a sourceof electromagnetic radiation and having a range that spans greater thanor equal to 50 nm, the emissive species associated with thechemical/biological species and detecting a detectable emission producedby the emissive species, wherein the detectable emission, if present,corresponds to the identity or characteristic of the chemical/biologicalspecies.

In some embodiments, the method comprises determining an identity orcharacteristic of a chemical/biological species by combining a firstelectromagnetic radiation signal and a second electromagnetic radiationsignal, wherein the first electromagnetic signal comprises at least afirst photon emission event occurring within 10 nanoseconds of anexcitation event that caused the first photon emission event, and asecond electromagnetic signal comprising at least a second photonemission event occurring after 10 nanoseconds of the excitation eventthat caused the second photon emission event, wherein the excitationevent comprises an electromagnetic radiation spectrum, wherein a firstportion of the electromagnetic radiation spectrum comprises a wavelengthof between 425 nm and 475 nm, and wherein a second portion of theelectromagnetic radiation spectrum comprises a wavelength of between 525nm and 725 nm.

In another aspect, kits are provided. In some embodiments, the kitcomprises an enclosure configured to receive a consumer electronicdevice, the consumer electronic device comprising a sensor and a sourceof electromagnetic radiation associated with the enclosure and/orconsumer electronic device, wherein the enclosure is configured toposition the consumer electronic device relative to an emissive species,if present, such that the sensor can detect a detectable emission fromthe emissive species, and the enclosure is configured to preventexternal light from interacting with the sensor.

Other advantages and novel features of the present invention will becomeapparent from the following detailed description of various non-limitingembodiments of the invention when considered in conjunction with theaccompanying figures. In cases where the present specification and adocument incorporated by reference include conflicting and/orinconsistent disclosure, the present specification shall control.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic diagram of an article and a chemical tagassociated with the article, according to one set of embodiments;

FIG. 1B is a schematic diagram of an article, a label, and a chemicaltag associated with the label, according to one set of embodiments;

FIG. 2 shows, according to some embodiments, an exemplary systemcomprising an excitation component, an image sensor, and an electronichardware component;

FIG. 3A shows a schematic plot of an exemplary rolling shuttermechanism, according to some embodiments;

FIG. 3B shows a schematic plot of an exemplary global shutter mechanism,according to some embodiments;

FIG. 4 shows, according to some embodiments, a single image of a pulsingLED captured by a smartphone using a rolling shutter method and a topcaption indicating whether the LED was on or off;

FIG. 5 shows images of a pulsing UV-LED exciting a fast emissive species(left) and a delayed emission species (right), according to someembodiments;

FIG. 6 shows, according to some embodiments, optical micrographs of athin film comprising two emissive species at 7° C., under refrigeration(left), at room temperature (center), and at 54° C., under heating(right);

FIG. 7 shows an optical micrograph of a vial containing multipleemissive species under steady illumination (left), an optical micrographof the same vial under pulsed illumination as imaged using rollingshutter (middle), and a magnified view of the middle optical micrograph(right), according to some embodiments.

FIG. 8 shows chromatographic images of an exemplary system, according toone set of embodiments;

FIG. 9 shows an exemplary negative assay result with a control linedetected in accordance with one or more inventions described herein,according to one set of embodiments;

FIG. 10 shown an exemplary positive assay result with an IgG linedetected in addition to a control line in accordance with one or moreinventions described herein, according to one set of embodiments;

FIG. 11 shows an exemplary negative assay result detected in accordancewith one or more inventions described herein, according to one set ofembodiments;

FIG. 12 shows an exemplary positive assay result detected in accordancewith one or more inventions described herein, according to one set ofembodiments;

FIG. 13 shows representative photographs of a Europium-based lateralflow assay imaged using a customized system in accordance with one ormore inventions described herein, according to one set of embodiments;

FIG. 14A shows a case configured to integrate with a smartphone,comprising a UV LED source and permits the camera of the smartphone tobe exposed, according to one set of embodiments;

FIG. 14B shows an exemplary holder comprising a portion configured toreceive the smartphone, and a sample port configure to receive a sample(e.g., an immunoassay cassette), according to one set of embodiments;

FIG. 14C shows an exemplary output from a custom smartphone softwarethat provides, for example, an image of the sample and a correspondingplot of intensity, according to one set of embodiments;

FIG. 14D shows an illustrative kit in accordance with one or moreinventions described herein, according to one set of embodiments;

FIG. 14E shows schematics of a design rendering of the rapid, point ofneed diagnostic, according to some embodiments;

FIG. 14F shows a schematics of a design rendering of the components ofthe diagnostic: set up tray with instructions for use (top left),integrated cassette and sample collection swab (top middle), smartphoneadapter (top right), and overall workflow (bottom), according to someembodiments;

FIG. 15A shows an image wherein an exemplary system has identified thearea of the key boundaries of an assay and the locations of the controland test signal, according to one set of embodiments;

FIG. 15B shows integrated line data corresponding to the image in FIG.15 , according to one set of embodiments; and

FIG. 16 shows representative photographs of Europium-based assays,according to one set of embodiments.

FIGS. 17A-17I demonstrate spectral outputs from exemplary sources ofelectromagnetic radiation associated with various consumer electronicdevices, according to some embodiments;

FIGS. 18A-18D shows images collected using collected using an iPhone 11and external (pulsed) white light LED of drop-cast samples of: FIG. 18A)Eu(fod)₃-MK; FIG. 18B) Eu(tta)₃(dpbt); FIG. 18C) Eu(tta)₃(bpt); and FIG.18D) Eu(pfppd)₃(tpy), according to some embodiments;

FIG. 19 shows samples of Eu(fod)₃-MK, with or without PMMA, drop-cast orspin-coated onto plain labels or labels pre-printed with a matrix (2D)barcode, according to some embodiments, with images collected using aniPhone 11 and external (pulsed) white light LED, with or without thepresence of room lighting;

FIGS. 20A-20B show samples of Eu(tta)₃(dpbt) in PMMA analyzed using a:FIG. 20A) a fluorimeter; FIG. 20B) an iPhone 11 with external (pulsed)white light LED, with or without the presence of room lighting,according to one set of embodiments;

FIG. 21 is a plot of fluorescence intensity versus excitation wavelengthfor a drop-cast sample of Eu(pfppd)₃(tpy) excited at various excitationwavelengths in a fluorimeter, according to one set of embodiments;

FIGS. 22A-22B show images of drop-cast samples of Eu(tta)₃(bpt) in aF8BT/PMMA mixture at: FIG. 22A) 0.6 mg/mL; and FIG. 22B) 1 mg/mL. Imageswere obtained using a commercially available flashlight app to strobethe white light LED of an iPhone 11, according to some embodiments; and

FIGS. 23A-23B show images of airbrushed samples of Eu(tta)₃(bpt) in aF8BT/PMMA analyzed with (FIG. 23A) or without (FIG. 23B) the presence ofroom lighting, according to one set of embodiments, with images obtainedusing a commercially available flashlight app to strobe the white lightLED of an iPhone 11.

FIGS. 24A-24B show images of a sample of Erythrosin B, a commerciallyavailable food coloring, incorporated into a Poly Vinyl Alcohol (PVA)matrix. The sample was imaged using an iPhone 11 under ambient (room)lighting (FIG. 24A) and in the dark using an external (pulsed) whitelight LED (FIG. 24B).

FIGS. 25A-25B show images of a sample of tan colored leather, withauthentication tag airbrushed on top. The sample was imaged with aniPhone 11 using a custom application (app) and pulsed UV LED excitationsource, with pulsed UV light source off (FIG. 25A) and on (FIG. 25B) ina lit room, according to some embodiments; and

FIGS. 26A-26B show images of a sample of blue colored leather, withauthentication tag airbrushed on top. The sample was imaged with aniPhone 11 using a custom application (app) and pulsed UV LED excitationsource with the pulsed UV light source off (FIG. 26A) and on (FIG. 26B)in a lit room, according to some embodiments; and

FIGS. 27A-27B show images of a clear glass, alcohol filled perfumebottle, with authentication tag airbrushed on one side. The sample wasimaged with an iPhone 11 using a custom application (app) and pulsed UVLED excitation source with the pulsed UV light source off (FIG. 27A) andon (FIG. 27B) in a lit room, according to some embodiments; and

FIGS. 28A-28B show images of a white cardboard box, with authenticationtag (smart logo) airbrushed on one side. The sample was imaged with aniPhone 11 using a custom application (app) and pulsed UV LED excitationsource, with the pulsed UV light source off (FIG. 28A) and on (FIG. 28B)in a lit room, according to some embodiments; and

FIGS. 29A-29B show images of a printed 2D (matrix) barcode on a whitelabel, with authentication tag airbrushed on top. The sample was imagedwith an iPhone 11 using a custom application (app) and pulsed UV LEDexcitation source, with the pulsed UV light source off (FIG. 29A) and on(FIG. 29B) in a lit room, according to some embodiments; and

FIGS. 30A-30B show images of a printed 2D (matrix) barcode on a whitebox, with authentication tag airbrushed on top. The sample was imagedwith an iPhone 11 using a custom application (app) and pulsed UV LEDexcitation source, with the pulsed UV light source off (FIG. 30A) and on(FIG. 30B) in a lit room, according to some embodiments; and

FIGS. 31A-31B shows images of a printed 2D (matrix) barcode on a blacknotebook, with authentication tag airbrushed on top. The sample wasimaged with an iPhone 11 using a custom application (app) and pulsed UVLED excitation source, with the pulsed UV light source off (FIG. 31A)and on (FIG. 31B) in a lit room, according to some embodiments;

FIG. 32A shows an image of a drop-cast sample of Eu(fod)₃-MK on a glasscoverslip, imaged with an iPhone 11 using a custom application (app) andpulsed excitation source. The images were collected using the same ISOsetting but different shutter speeds. The top half of the coverslip hadbeen exposed to diethylamine for 2 minutes, the bottom half had not beenexposed, according to some embodiments;

FIG. 32B shows an image of a drop-cast sample of Eu(fod)₃-MK on a glasscoverslip, imaged with an iPhone 11 using a custom application (app) andpulsed excitation source. The images collected using the same ISOsetting but different shutter speeds. The top half of the coverslip hadbeen exposed to water for 15 minutes, the bottom half had not beenexposed, according to some embodiments;

FIGS. 33A-33B show images of a drop-cast sample of PdOEP on a glasscoverslip in an air-free environment inside a vacuum chamber, imagedwith an iPhone 11 and pulsed white light LED excitation source, before(FIG. 33A) and after (FIG. 33B) exposure to air/oxygen, according tosome embodiments; and

FIGS. 34A-34B show images of a cast film of PdOEP inside a glass vial,imaged with an iPhone 11 using a custom application (app) and pulsedwhite light LED excitation source, before (FIG. 34A) and after (FIG.34B) exposure to air/oxygen, according to some embodiments; and

FIG. 35A shows chemical structures of exemplary oligomeric/polymericwhite light excitable Eu-based delayed emitters (PCBH)₆Eu₂(Phen)₂,(PCBH)(PCH)Eu(Phen), and (PCBH)(PCH)Eu(bpt), according to someembodiments; and

FIG. 35B-35C show images of a solid sample of (PCBH)(PCH)Eu(bpt) in aglass vial (FIG. 35B) and drop-cast on white paper (FIG. 35C), imagedwith an iPhone 11 using a custom application (app) and the iPhone'sflash LED.

Other aspects, embodiments and features of the invention will becomeapparent from the following detailed description when considered inconjunction with the accompanying drawings. The accompanying figures areschematic and are not intended to be drawn to scale. For purposes ofclarity, not every component is labeled in every figure, nor is everycomponent of each embodiment of the invention shown where illustrationis not necessary to allow those of ordinary skill in the art tounderstand the invention. All patent applications and patentsincorporated herein by reference are incorporated by reference in theirentirety. In case of conflict, the present specification, includingdefinitions, will control.

DETAILED DESCRIPTION

In one aspect, compositions, articles, systems, and methods for sensingand/or authentication using imaging are generally provided, in someembodiments. In connection with these, an image (or series of images) ofone or more emissive species may be obtained, and time-dependence ofimage formation or manipulation may be leveraged to determine andidentify information about the species, on the timeframe of imageformation/obtaining.

In another aspect, some embodiments described herein generally relate todiagnostic assays and related methods. In connection with these, a firstphoton emission event (e.g., a steady state emission) and a second photoemission event (e.g., a non-steady state emission) may be detected andleveraged to determine and identify information about a chemical and/orbiological species (e.g., a reaction, the presence of, etc.).

In another aspect, some embodiments described herein generally relate totemporal thermal sensing and related methods.

In another aspect, some embodiments described herein generally relate tosystems and methods for identifying a characteristic and/or an identityof a chemical/biological species.

In yet another aspect, some embodiments are described herein generallyrelate to the ability to determine if an article is authentic or if anarticle has been modified.

In some cases, systems and methods described herein advantageously allowconsumers to use consumer-level electronics with imaging capabilities(e.g., a smartphone, a digital camera, a tablet, a laptop, a homeautomation device, a smartwatch, a desktop computer) to evaluate acharacteristic of an article (e.g., determine whether a product isauthentic, whether food is fresh, whether a contaminant or otherdangerous material is present). One factor that has limited the use ofconsumer-level electronics in conventional optical sensing applicationshas been the need to use optical filters (e.g., bandpass filters) toselectively emit electromagnetic radiation having a peak wavelength in arelatively narrow range (e.g., electromagnetic radiation configured toexcite one or more fluorophores) and to detect electromagnetic radiationhaving a peak wavelength in a relatively narrow range (e.g.,electromagnetic radiation emitted by the one or more fluorophores). Forexample, if a standard fluorophore (e.g., producing a detectablesteady-state photon emission event) were excited using substantiallywhite light emitted by the flash of a camera and/or smartphone, anemission from the fluorophore could be washed out by the overlappingreflected/scattered wavelengths present in white light. One solution tothis problem may involve placing a bandpass filter over a lens of acamera and/or smartphone to selectively permit wavelengths originatingfrom the fluorophore to enter the lens. Another solution may involveincorporating a source of electromagnetic radiation that selectivelyemits wavelengths that excite the fluorophore. However, these solutionsmay become prohibitively expensive and/or inconvenient if more than onefluorophore is used, as each fluorophore may require an additionalfilter and/or source of electromagnetic radiation. Advantageously,systems and methods described herein may not require an excitationcomponent or image sensor to be associated with different opticalfilters (e.g., bandpass filters) for different types of emissivespecies.

Advantageously, the systems and methods described herein may beimplemented on consumer-level electronics such as cellular phones (e.g.,smartphones, iPhones, Android phones), digital cameras, tablets (e.g.,iPads), laptop computers, home automation devices, watches (e.g.,smartwatches), and/or desktop computers. These consumer electronics maybe used with filters or other accessories, but in some cases for themethods described herein, such filters will not be required. However,the systems and methods are not limited to consumer-level electronicsand may be implemented on other systems and devices as well.

In some embodiments, a system comprises an image sensor. An image sensoris generally configured to detect electromagnetic radiation (e.g.,detectable emissions from emissive species) and to output signals (e.g.,electrical signals) that may be used to generate an image. Any suitabletype of image sensor may be used to detect an emission (or absence of anemission) from an emissive species under a particular set of conditions.Non-limiting examples of suitable image sensors include complementarymetal oxide semiconductor (CMOS) sensors, charge-coupled device (CCD)sensors, and photodiodes. Those of ordinary skill in the art would becapable of selecting suitable image sensors based upon the teachings ofthis specification. The image sensor may be configured, in someembodiments, with an accompanying excitation source component to detectlight emitted from steady-state photon emission events and/ornon-steady-state photon emission events.

Turning now to the figures, as illustrated in FIG. 1A, in someembodiments, system 100 comprises an article 110 and a chemical tag 120associated with article 110. In some embodiments, chemical tag 120comprises one or more emissive species. In some embodiments, asdescribed herein, the one or more emissive species may identifycharacteristic of article 110. In some embodiments, sensor 140 may beused to detect the presence (or absence) of chemical tag 120 and/or theone or more emissive species chemical tag 120 comprises. In someembodiments, chemical tag 120 may be positioned proximate, adjacent, ordirectly adjacent article 110.

In some embodiments, the chemical tag is associated with the article andadjacent (e.g., directly adjacent) a label, the label associated withthe article. For example, as illustrated in FIG. 1B, system 102comprises article 110 and chemical tag 120 associated with article 110.In some embodiments, a label 130 is associated with article 110. In someembodiments, chemical tag 120 is associated with label 130. In someembodiments, label 130 comprises one or more compounds forming chemicaltag 120. In some embodiments, the label is adjacent the article. In someembodiments, the label is directly adjacent (e.g., affixed to) thearticle. In some embodiments, the label is proximate the article but notnecessarily adjacent the article. For example, in some embodiments, thelabel may be present in a container containing at least a portion of thearticle.

FIG. 2 illustrates an exemplary system. In FIG. 2 , system 200 comprisesexcitation component 210. In some cases, excitation component 210comprises a source of electromagnetic radiation. As one non-limitingexample, excitation component 210 may comprise a source of substantiallywhite light. In some instances, excitation component 210 is a source ofone or more narrow bands of different wavelengths of electromagneticradiation, and/or polarized electromagnetic radiation. In someinstances, excitation component 210 is associated with an electronicand/or mechanical shutter. The electronic and/or mechanical shutter maybe configured to modulate electromagnetic radiation emitted byexcitation component 210. In other cases, the excitation component 210is driven by periodic or pulsed electrical energy that causes flashesand/or modulation in the output intensity. In some cases, the excitationcomponent 210 could be “room light,” such as a fluorescent or LED lightsource. In some embodiments, system 200 further comprises image sensor220 (e.g., a CMOS sensor, a CCD sensor, photodiode array, or otherdetector capable of detecting electromagnetic radiation). In some cases,system 200 further comprises electronic hardware component 230 (e.g.,circuitry, one or more processors). In certain instances, electronichardware component 230 is integrated with image sensor 220. In certainother instances, electronic hardware component 230 is separate fromimage sensor 220. In some embodiments, system 200 is a consumer-levelelectronic device, such as a cellular phone (e.g., a smartphone), adigital camera, a tablet, a laptop, a home automation device, a watch(e.g., a smartwatch), or a desktop computer.

In operation, system 200 may be positioned in proximity to article 240,which may be associated with one or more emissive species. Proximity canrange from centimeters to multiple meters and may be determined by thesize of article 240, the resolution of image sensor 220, and theinformation that is required. The orientation of article 240 and imagesensor 220 may also be varied, with different orientations (e.g. angles,front/back, tilts) allowing for different information to be extracted.In some cases, other information gleamed by a device from article 240,or given by an external source, will inform the orientation andproximity required. Excitation component 210 may emit pulsed and/ormodulated electromagnetic radiation 250, which may be absorbed by theone or more emissive species of article 240. This radiation may be indiscrete narrow bands of wavelength or be in broad bands (such as whitelight). Excitation component 210 can simultaneously produce multipledifferent patterns of electromagnetic radiation at different wavelengthsthat vary in their time modulation, intensity, polarization, and thephysical location upon which they impinge on article 240. In some cases,the electromagnetic radiation is absorbed by a first species thattransfers energy to a second emissive species of article 240. In somecases, at least a portion of electromagnetic radiation 250 may excite orbe reflected or scattered by the one or more emissive species of article240. Reflected or scattered radiation may be generated by excitationcomponent 210 or be the result of ambient light. The one or moreemissive species may subsequently produce detectable emission 260 overan emission time period (e.g., emission lifetime). Image sensor 220 maydetect at least a portion of detectable emission 260. Image sensor 220may also detect at least a portion of reflected or scatteredelectromagnetic radiation. In some cases, detection of detectableemission 260 may begin after excitation component 210 has stoppedemitting electromagnetic radiation 250. In certain instances, this maypermit the use of a substantially white light source (e.g., a cameraflash) as excitation component 210. In certain instances,electromagnetic radiation 260 is constantly varying in time as a resultof the lifetime of emissive species of article 240 and a modulatedexcitation by excitation component 210. In some cases, electronichardware component 230 generates a single image (or a series of images)comprising a first portion corresponding steady-state andnon-steady-state photon emission. In some cases, the image is generatedby measuring many different emission time periods, and/or with manydifferent excitation methods, and/or at different distances, and/or withdifferent orientations, and/or with different filters or polarizers. Insome cases, electronic hardware component 230 receives instructions fromarticle 240 and/or another source that changes the overall method ofexcitation and image capture. In some instances, a characteristic of anemissive species and/or a change in an emissive species is determinedbased upon a difference between the first portion of the single image(or series of images) and the second portion of the single image (orseries of images). Many different time periods may be captured usingthis method. In certain non-limiting instances, an emission lifetime, orrelative change in an emission lifetime, of an emissive species isdetermined from the single image or series of images (e.g., based upon adifference between the first portion of the single image or series ofimages and the second portion of the single image or series of images).In some cases, a characteristic of the article is determined from thesingle image or series of images (e.g., based upon a difference betweenthe first portion of the single image or series of images and the secondportion of the single image or series of images). In certain instances,a series of single images may be used to generate different sets of data(e.g., characteristics) from each single image by comparing, forexample, different portions of each image over time.

In some embodiments, an image sensor uses a rolling shutter method ofimage capture, as described in more detail below. An image sensor oftencomprises an array of photodetectors (e.g., corresponding to one or morepixels), and in a rolling shutter method, individual rows or columns aresequentially read. Thus, in a single frame captured using a rollingshutter method, each row or column (depending on the particular rollingshutter method) represents a slice of time. To illustrate, FIG. 3A showsa plot of an exemplary rolling shutter mechanism in which individualrows are sequentially read. Rolling shutter methods may be implementedmechanically or electronically.

In contrast, in a global shutter method, all pixels of an image sensorare simultaneously exposed to the photon emission and then read. Toillustrate, FIG. 3B shows a plot of an exemplary global shuttermechanism in which all rows are simultaneously excited. This is thecase, for example, with photographic film wherein a global shutter isused and all points on the film are exposed at the same time. In someembodiments, the image sensor uses a global shutter method of imagecapture, as described in more detail below.

In some embodiments, the system comprises an excitation componentconfigured to excite an emissive species. Without wishing to be bound bytheory, some optical emissions are generally effectively instantaneousand may include the reflection or scattering of electromagneticradiation. In some embodiments, such emissions may be wavelengthdependent and/or may be affected by the absorption of certainwavelengths (e.g., subtractive color). In the case of reflected orscattered light, without wishing to be bound by theory, photons may notbe able to promote electrons to higher energy states in the material.Such processes are generally very fast. In some cases, for scatteringand reflection by way of example, the photons interact with the materialat very short time scales that may have excited state lifetimes shorterthan picoseconds. Other emission events such as fluorescence andphosphorescence generally involve the promotion of electrons to higherenergy states with the absorption of a photon. For example, relativelyfast emissions may occur from materials displaying prompt fluorescence,wherein the emitter has an excited state lifetime less than 10nanoseconds (ns). In some embodiments, these relatively fast emissions(and, in some embodiments all emissions) are detected/imaged understeady-state conditions wherein emission is detected while a constantexcitation source is applied to an article of interest. In some suchembodiments, the detectable signal is produced from a steady-statephoton emission. In some embodiments, the excited state lifetime of anemissive material is long-lived (e.g., with an excited state lifetime 10ns or more), such that additional information may be captured undernon-steady state conditions wherein the emission varies over the courseof a measurement. In some embodiments, capture of such additionalinformation may involve data capable of generating one or more images.The non-steady state measurement is performed, in some embodiments, byusing a non-steady-state excitation source that is pulsing, flashing,and/or modulated. By way of example, a long-lived emitter with anexcited state lifetime more than 10 ns may continue, in someembodiments, to emit light after the excitation is removed or after theexcitation intensity is changed. This may result, in some cases, in thelong-lived emission to be selectively detected in the presence ofemissive species with lifetimes less than 10 ns. The modulation may beperformed, in some embodiments, by changes in intensity some or all ofthe wavelengths of light in time, or by changes in the polarization oflight as a function of time. The modulation may, in some cases, becontinuous in the form of a sine wave form, or can be a triangular waveform, or a square waveform. The modulation comprises, in someembodiments, a switch between entirely off (no excitation) to fully on(maximum intensity excitation) and/or comprises involving a modulationon a particular base intensity. In some embodiments, modulationcomprises the modulation of a particular wavelength on a base intensity.By way of example and without wishing to be limited as such, a broadband of light that emulates natural light, e.g., white light, may be thebase constant signal and an ultraviolet light signal may be used as themodulated signal. In this way, ascattering/reflection/prompt-fluorescence photon emission detection maybe collected at the same time as a non-steady-state photon emissiondetection. Modulation of the excitation may result, in some embodiments,in a modulated emission intensity and in the case that the emissivematerials have lifetimes less than 10 ns then the emission under certainconditions will have a modulated intensity that is in phase with theexcitation light. However, if long-lived emitters with lifetimes morethan 10 ns are present then under some conditions a phase shift mayresult, in some embodiments, in the emission intensity.

In some embodiments, the system comprises an excitation componentconfigured to excite an emissive species. Without wishing to be bound bytheory, some optical emissions are generally effectively instantaneousand may include the reflection or scattering of electromagneticradiation. In some embodiments, such emissions may be wavelengthdependent and/or may be affected by the absorption of certainwavelengths (e.g., subtractive color). In the case of reflected orscattered light, without wishing to be bound by theory, photons may notbe able to promote electrons to higher energy states in the material.Such processes are generally very fast. In some cases, for scatteringand reflection by way of example, the photons interact with the materialat very short time scales that may have excited state lifetimes shorterthan picoseconds. Other emission events such as fluorescence andphosphorescence generally involve the promotion of electrons to higherenergy states with the absorption of a photon. For example, relativelyfast emissions may occur from materials displaying prompt fluorescence,wherein the emitter has an excited state lifetime less than 10nanoseconds (ns). In some embodiments, these relatively fast emissions(and, in some embodiments all emissions) are detected/imaged understeady-state conditions wherein emission is detected while a constantexcitation source is applied to an article of interest. In some suchembodiments, the detectable signal is produced from a steady-statephoton emission. In some embodiments, the excited state lifetime of anemissive material is long-lived (e.g., with an excited state lifetime 10ns or more), such that additional information may be captured undernon-steady state conditions wherein the emission varies over the courseof a measurement. In some embodiments, capture of such additionalinformation may involve data capable of generating one or more images.The non-steady state measurement is performed, in some embodiments, byusing a non-steady-state excitation source that is pulsing, flashing,and/or modulated. By way of example, a long-lived emitter with anexcited state lifetime more than 10 ns may continue, in someembodiments, to emit light after the excitation is removed or after theexcitation intensity is changed. This may result, in some cases, in thelong-lived emission to be selectively detected in the presence ofemissive species with lifetimes less than 10 ns. The modulation may beperformed, in some embodiments, by changes in intensity some or all ofthe wavelengths of light in time, or by changes in the polarization oflight as a function of time. The modulation may, in some cases, becontinuous in the form of a sine wave form, or can be a triangular waveform, or a square waveform. The modulation comprises, in someembodiments, a switch between entirely off (no excitation) to fully on(maximum intensity excitation) and/or comprises involving a modulationon a particular base intensity. In some embodiments, modulationcomprises the modulation of a particular wavelength on a base intensity.By way of example and without wishing to be limited as such, a broadband of light that emulates natural light, e.g., white light, may beused as the base constant signal and/or an ultraviolet light signal maybe used as the modulated signal. In this way, in some embodiments, ascattering/reflection/prompt-fluorescence photon emission detection maybe collected at the same time as a non-steady-state photon emissiondetection. Modulation of the excitation may result, in some embodiments,in a modulated emission intensity, and in the case that the emissivematerials have lifetimes less than 10 ns, then the emission undercertain conditions may have a modulated intensity that is in phase withthe excitation light. However, in some embodiments, long-lived emitterswith lifetimes more than 10 ns are present and, under some conditions, aphase shift may result in the emission intensity.

In some embodiments, the system comprises an excitation componentconfigured to excite the emissive species e.g., in a way that allows forthe detection of non-steady-state photon emission. In embodimentscomprising a pulsed excitation, a steady-state emission may be detectedwhile the steady-state excitation is applied and after the pulsedexcitation, when there is no excitation, then the non-steady-stateemission may be detected. In some embodiments, a non-steady-state (e.g.,time varying) excitation enables the detection of both a steady-statephoton emission and a non-steady-state photon emission. Similarly, inembodiments in which a modulated non-steady-state excitation is used,e.g., wherein the steady-state emission has a modulated intensity thatis in phase with the modulated excitation, the non-steady-state emissionhas a phase lag with an appropriate paring of the emissive species andthe cycle time (frequency) of the modulation. In some embodiments, thesystem comprises an image sensor configured to detect at least a portionof electromagnetic radiation emitted by the emissive species. In someembodiments, the system comprises an electronic hardware componentconfigured to collect data and/or produce a single image comprising atleast a first image portion corresponding to emission of electromagneticradiation by the emissive species at least at a first point in time, anda second image portion corresponding to emission of electromagneticradiation by the emissive species at least at a second point in time. Insome embodiments, the electronic hardware component is configured tocollect data and/or produce a single image comprising a steady-statephoton emission and a non-steady-state photon emission. In someembodiments, the system separately detects a steady-state photonemission and a non-steady-state photon emission.

In some embodiments, the system comprises a chemical tag associated withthe article. In some embodiments, the chemical tag comprises an emissivespecies. In some embodiments, the emissive species produces a detectablenon-steady-state emission during emission time periods under a set ofconditions. In some embodiments, the emission time period is at least 10nanoseconds. In some embodiments, the emissive species produces adetectable steady-state and non-steady-state emission during emissiontime periods under a set of conditions. In some embodiments, the systemcomprises an excitation component configured to excite the emissivespecies under the set of conditions such that the detectablenon-steady-state emission, which varies over the image capture timeperiod, is produced. In some embodiments, the system comprises an imagesensor configured to detect the detectable emission. In someembodiments, the system comprises an electronic hardware componentconfigured to convert the detectable emission into a single image. Forexample, data created from photon emission events or differentwavelengths and intensity (steady-state and non-steady state) may beused to create an image. In some embodiments, devices (e.g.,smartphones, consumer electronic devices) that capture images are usedgenerate photon emission data including intensity spatial relationshipsand information about the excited state lifetimes. In some embodiments,photon emission data comprises a signal and/or a detection. In someembodiments, data collected from a photo emission is used to generateone or more images. Some embodiments comprises a combination of one ormore of images, data, signals, measurements, and detection pertaining tophoton emission(s).

In some embodiments, an image (or associated data) is used to determinethe most relevant photon emission signal(s) for detection to identify acharacteristic of an article. In some embodiments, the system comprisesan excitation component configured to excite the photon emissive speciesunder the set of conditions to produce a detectable non-steady-statephoton emission, which varies over the photon emission and/or imagecapture time period. In some embodiments, the system comprises an imagesensor configured to detect the detectable photon emission. In someembodiments, the system comprises an electronic hardware componentconfigured to convert the detectable photon emission data into one ormore images. In some embodiments multiple images are used to identify acharacteristic of an article that may be determined from one or moresteady-state or non-steady-state photon emission measurements. In someembodiments, only a non-steady-state photo emission signal and/or imagecollected under non-steady-state conditions is used for identificationof a characteristic of an article. In some embodiments, multiple(different) non-steady-state photon emission signals are used foridentification of a characteristic of an article. In some embodiments,photon emission data or images from multiple locations of an article areused for identification of a characteristic of an article. In someembodiments, a single image is created by both steady-state andnon-steady-state photon emission events for identification of acharacteristic of an article. In some embodiments, a steady-stateemission is used in conjunction with a non-steady state emission foridentification of a characteristic of an article. In some embodiments asteady-state emission is used to determine the conditions upon which oneor more non-steady-state photon emission measurements are performed. Insome embodiments, multiple images are taken under different excitationconditions. In some embodiments, the excitation conditions involve oneor more of the following excitation conditions: pulses, flashes,continuous intensity, modulation at a single frequency, and modulationat multiple frequencies. In some embodiments, the excitation is providedby a white light source. In some embodiments, narrow bands of light areused to excite an emissive species. In some embodiments, only one bandof light is used for each image. In some embodiments, multiple bands ofwavelength of electromagnetic radiation are used to excite an emissivespecies. In some embodiments, multiple excitations are used to createmultiple steady-state and/or non-steady photon emission events foridentification of a characteristic of an article.

In some embodiments, a single image comprises a first portioncorresponding to a first portion of the emission time period and asecond portion corresponding to a second portion of the emission timeperiod. In some embodiments, a difference between a property of thefirst portion and the second portion is associated with a characteristicof the article.

In some embodiments, the system comprises a chemical tag associated withthe article. In some embodiments, the chemical tag comprises an emissivespecies. In some embodiments, the chemical tag produces a detectablenon-steady-state emission during an emission time period under a set ofconditions. In some embodiments, the emission time period is at least 10nanoseconds. In some embodiments, the system comprises an excitationcomponent configured to excite the emissive species under the set ofconditions such that the detectable non-steady-state emission, whichvaries over the data/image capture time-period, is produced. In someembodiments, the system comprises an image sensor configured to detectthe detectable non-steady-state emission. In some embodiments, thesystem comprises an electronic hardware component configured to convertthe detected emission into a single image. In some embodiments, thesystem comprises an image sensor configured to detect the detectablenon-steady-state photon emission. In some embodiments, the systemcomprises an image sensor configured to detect both a detectablesteady-state emission and a detectable non-steady-state photon emission.In some embodiments, the system comprises an electronic hardwarecomponent configured to convert the detected emission data into a singleimage. In some embodiments, the image created from the non-steady statephoton emission is recognizable by visual inspection by a user and mayprovide information about the characteristic of an article. In someembodiments, the image is created by both steady-state emission andnon-steady-state photon emission processes. In some embodiments, aseries of images are generated from data collected under one or moredifferent steady-state and non-steady-state conditions as describedherein, and under one or more image sensor conditions, to provideinformation about the characteristic of an article. In some embodiments,images are generated by data from the detection of multiplenon-steady-state photon emission events to provide information about thecharacteristic of an article. In some embodiments, images are created bythe detection of one or more different steady-state photon emission andnon-steady-state photon emission events that provide information aboutthe characteristic of an article. In some embodiments, a plurality ofnon-steady-state photon emission events provide information about thecharacteristic of an article.

In some embodiments, a system configured for identification of acharacteristic of a chemical tag is provided. In some embodiments, thesystem comprises a chemical tag. In some embodiments, the chemical tagproduces a detectable photon emission under non-steady-state conditions.In some embodiments, one of more emissive species contribute to thenon-steady-state emission that have excited state lifetimes of least 10nanoseconds. In some embodiments, the system comprises an excitationcomponent configured to excite the chemical tag under the set ofconditions such that the detectable emission is produced. In someembodiments, the system comprises an image sensor configured to detectthe detectable photon emission. In some embodiments, the systemcomprises an electronic hardware component configured to convert thedetected emission into a single image. In some embodiments, the singleimage comprises steady-state and non-steady-state photon emissionevents. In some embodiments, a difference between a property of thesteady-state and non-steady-state is associated with a characteristic ofthe chemical tag.

In some embodiments, the single image comprises a first portioncorresponding to a first portion of the emission time period and asecond portion corresponding to a second portion of the emission timeperiod. In some embodiments, a difference between a property of thefirst portion and the second portion is associated with a characteristicof the chemical tag.

In some embodiments, methods described herein comprise exciting thespecies such that it produces a detectable non-steady-state emissionduring an emission time period. In some embodiments, the excited stateemission lifetime of one or more of the emissive species is at least 10ns. In some embodiments, the method comprises obtaining, using an imagesensor, capable of collecting photon emission data, a single image ofwhich has at least a portion of the detectable non-steady-state photonemission. In some embodiments, a first portion of the single imagecorresponds to a steady-state emission. In some embodiments, a secondportion of the single image corresponds to a non-steady-state emission.In some embodiments, the method comprises determining, based upon adifference between the steady-state and non-steady-state emission. Insome embodiments, the method comprises determining the differencebetween multiple non-steady-state emissions. In some embodiments, themethod comprises determining the difference between multiplesteady-state and non-steady-state emissions.

In some embodiments, a method for identifying a change in an emissivespecies over a period of time is provided. In some embodiments, themethod comprises causing the species to emit such that anon-steady-state photon emission is detectable during an emission timeperiod. In some embodiments, the method comprises obtaining, using animage sensor, a single image of at least a portion of theelectromagnetic radiation emitted is a non-steady-state emission. Insome embodiments, the method comprises identifying information from afirst image portion corresponding to emission of electromagneticradiation by the emissive species at least at a first point in time. Insome embodiments, the method comprises identifying information from asecond image portion corresponding to emission of electromagneticradiation by the emissive species at least at a second point in time. Insome embodiments, the method comprises determining, from at least theinformation from the first image portion and the information from thesecond image portion, the change in the emissive species.

In some embodiments, a method for identifying a characteristic of anemissive species is provided. In some embodiments, the method comprisesexciting the species such that the species produces a detectablenon-steady-state emission during an emission time period. In someembodiments, the emission is produced by an emissive species having anexcited state lifetime of at least 10 nanoseconds. In some embodiments,the method comprises obtaining, using an image sensor, a first image ofthe detectable non-steady-state emission. In some embodiments, a firstportion of the first image corresponds to a first portion of theemission time period. In some embodiments, a second portion of the firstimage corresponds to a second portion of the emission time period. Insome embodiments, the method comprises determining, based upon adifference between the first portion and the second portion of the firstimage, the characteristic of the species.

In some embodiments, a method for identifying a characteristic of anarticle is provided. In some embodiments, the method comprisespositioning an image sensor proximate an article suspected of containingan emissive tag. In some embodiments, the method comprises stimulatingthe article such that the emissive tag, if present, produces adetectable non-steady-state emission. In some embodiments, the methodcomprises obtaining, using the image sensor, a single image of which atleast a portion is a detectable non-steady-state photon emission. Insome embodiments, the conditions for the detection of thenon-steady-state photon emission are informed by a steady-state image.In some embodiments, the method comprises adding a sample of the articleto be analyzed to a second article, and then analyzing the secondarticle with an image sensor. In some embodiments, a first portion ofthe single image corresponds to a first time period after stimulatingthe analyte. In some embodiments, a second portion of the single imagecorresponds to a second time period after stimulating the analyte,different than the first time period. In some embodiments, the methodcomprises determining, based upon a difference between the first portionand the second portion of the single image, the characteristic of thearticle.

In some embodiments, a method for detecting the presence of a stimulusis provided. In some embodiments, the method comprises exposing anarticle comprising a chemical tag to a set of conditions comprising thestimulus. In some embodiments, the chemical tag undergoes a chemicaland/or biological reaction or association in the presence of thestimulus that changes the lifetime, wavelength, and/or intensity of oneor more emissive species in the tag. In some embodiments, the methodcomprises positioning an image sensor proximate the article. In someembodiments, the method comprises obtaining, using the image sensor, asingle image of a portion of the article comprising the chemical tag. Insome embodiments, a first portion of the single image corresponds to afirst time period after exposing the article (e.g., to electromagneticradiation, to a stimulus). In some embodiments, a second portion of thesingle image corresponds to a second time period after exposing thearticle (e.g., to electromagnetic radiation, to a stimulus), differentthan the first time period. In some embodiments, the method comprisesdetermining, based upon a difference between the first portion and thesecond portion of the single image, the characteristic of the article.In some embodiments, the method may be extended to obtain and useinformation from additional portions of the images at multiple points intime. In some embodiments, the portions are analyzed with plane orcircularly polarized light, different wavelengths of light, or othernon-steady-state electromagnetic radiation. In some embodiments, themethod comprises exciting one or more emissive species associated withan article and detecting, using a detector, a detectable delayedemission of the emissive species, wherein the detectable delayedemission, if present, has a delayed emission with an excited statelifetime greater than or equal to 10 nanoseconds, and wherein thedetectable delayed emission, if present, corresponds to an exposure ofthe article to a temporal thermal history.

In some embodiments, the method comprises exciting one or more firstemissive species, optionally, exciting one or more second emissivespecies, detecting, using a detector, a first detectable delayedemission(s) produced by the first emissive species and/or a seconddetectable delayed emission(s) produced by the second emissive species,wherein, the first detectable delayed emission, if present, correspondsto exposure of the first emissive species to a first temperature, andwherein, the second detectable delayed emission, if present, correspondsto exposure of the second emissive species to a second temperature,different than the first temperature, wherein, at least one detectabledelayed emission is present.

In some embodiments, a composition comprising an emissive species isconfigured to be associated with an article, wherein excitation of theemissive species produces a detectable signal having one or moreemissive species with excited state lifetimes than or equal to 10nanoseconds, and wherein the detectable signal corresponds to a temporalthermal history of the article.

In some embodiments, the system comprises an excitation componentconfigured to excite, using electromagnetic radiation, an emissivespecies such that, if single or multiple emissive species, or theirprecursors, were exposed to a temporal thermal history, produces adetectable delayed emission with an excited state lifetime greater thanor equal to 10 nanoseconds and a detector configured to detect at leasta portion of the detectable delayed emission.

In some embodiments, the system comprises one or more components of adiagnostic assay. In some embodiments, the method comprises determiningan identity or characteristic of a chemical/biological species bycombining a first electromagnetic radiation signal comprising at least asteady-state photon emission event, and a second electromagneticradiation signal comprising at least a non-steady-state photon emissionevent. In some embodiments, the method comprises determining an identityor characteristic of a chemical/biological species by combining a firstelectromagnetic radiation signal and a second electromagnetic radiationsignal, wherein the first electromagnetic signal comprises at least afirst photon emission event from an emissive species with an excitedstate lifetime less than 10 nanoseconds. This emission is detected understeady-steady state conditions. A second electromagnetic signalcomprising at least a second photon emission event from an emissivespecies with an excited state lifetime of at least 10 nanosecondsdetected under non-steady-state conditions. In some embodiments, animage is collected after a non-steady-state pulsed emission and only anon-steady-state photon emission is detected. In some embodiments, animage is collected over the time period wherein one or more parts of theimage are obtained with a steady-state excitation to detect steady-statephoton emission and one or more parts of the image are obtained afterthe excitation is removed to enable the detection of a non-steady-statephoton emission.

In some embodiments, a first photon emission event comprises an emissionproduced by an emissive species having an excited state lifetime of lessthan or equal to 10 nanoseconds. In some embodiments, a second photonemission event comprises an emission produced by an emissive specieshaving an excited state lifetime of at least 10 nanoseconds.

In some embodiments, the method comprises detecting two or more signalsemanating from an assay, wherein each of the two or more signals areselected from a subtractive color, reflected color, scattering,chemiluminescence, prompt-fluorescence, delayed-fluorescence,prompt-phosphorescence, and delayed-phosphorescence emission.

In some embodiments, the system comprises an excitation componentconfigured to excite a first emissive species such that the firstemissive species produces a detectable steady-state photon emission, theexcitation component is configured to excite a second emissive speciessuch that the second emissive species produces a detectablenon-steady-state photon emission, and a sensor configured to detect atleast a portion of the detectable steady-state photon emission and atleast a portion of the detectable non-steady-state emission.

In some embodiments, the system comprises an electronic hardwarecomponent configured to combine the detectable steady-state emission andthe detectable non-steady-state emission into a determinable signal. Insome embodiments, the detectable steady-state emission and/or thedetectable non-steady-state emission correspond to a characteristic ofthe first emissive species and/or the second emissive species,respectively, as described herein.

In an exemplary set of embodiments, the system comprises a source of anelectromagnetic radiation spectrum and an emissive species, wherein afirst portion of the electromagnetic radiation spectrum comprises awavelength of between 425 nm and 475 nm, wherein a second portion of theelectromagnetic radiation spectrum comprises a wavelength of between 525nm and 725 nm, and wherein the source produces a wavelength ofelectromagnetic radiation that interacts with the emissive species suchthat the emissive species produces a detectable signal having one ormore delayed emissions from emissive species having excited statelifetimes greater than or equal to 10 nanoseconds.

In some embodiments, the system comprises a source of a plurality ofwavelengths of electromagnetic radiation and an emissive species,wherein the emissive species produces a detectable signal having one ormore delayed emissions of greater than or equal to 10 nanoseconds, andwherein the plurality of wavelengths of electromagnetic radiationgenerated by the source spans greater than or equal to 50 nm. In someembodiments, a detectable signal is read using a smartphone or digitalcamera.

In some embodiments, the system comprises a source of electromagneticradiation associated with a consumer electronic device, a sensorassociated with the consumer electronic device, and an emissive speciescapable of producing a detectable signal by the sensor, the detectablesignal having one or more delayed emissions from an emissive specieshaving an excited state lifetime greater than or equal to 10nanoseconds. In some embodiments, the source is a component of aconsumer electronic device. In some embodiments, the consumer electronicdevice is a smartphone, tablet, computer, digital camera, or the like.

In some embodiments, the electromagnetic radiation produced by thesource is unadulterated prior to exposure to the emissive species. Insome embodiments, the system does not comprise a light filter positionedbetween the source and the emissive species.

In some embodiments, the system comprises an excitation componentconfigured to produce a plurality of wavelengths of electromagneticradiation, wherein the excitation component is configured to excite afirst emissive species such that the first emissive species produces adetectable stead-state photon emission signal, the excitation componentis configured to excite a second emissive species such that the secondemissive species produces a detectable non-steady-state photon emissionsignal, and a sensor configured to detect at least a portion of thedetectable steady-state photon emission signal and at least a portion ofthe detectable non-steady-state emission signal.

In some embodiments, the system comprises a radiation source configuredto generate a plurality of wavelengths of electromagnetic radiation forexciting an emissive species such that the emissive species produces adetectable non-steady-state emission during an emission time period, theexcited state lifetime of the emissive species being least 10nanoseconds.

In some embodiments, the system comprises a sensor and processingcircuitry configured to detect both steady-state and non-steady-statephoton emissions in a given image, wherein the steady-state photonemission is detected while the emissive species is undergoing excitationand the non-steady-state photon emission is collected after theexcitation is turned off. In some such embodiments, a pulsed excitationis used and the pulsing rate is selected to be about the same or fasterthan the image capture rate. Advantageously, in some such embodiments,multiple images may be combined containing information from bothsteady-state and non-steady state photon emissions. Advantageously, insome embodiments, excitation and emission capture need not necessarilybe synchronized and computational methods may be used to extract datafrom the images.

In some embodiments, the method comprises using a consumer electronicdevice to determine an identity or characteristic of achemical/biological species, wherein the consumer electronic devicecomprises a source of a spectrum of electromagnetic radiation andexposing an emissive species to the spectrum of electromagneticradiation such that the emissive species produces a detectable emissionwhich corresponds to the identity or characteristic of thechemical/biological species and which is detectable by the consumerelectronic device. In some embodiments, the method comprises determiningan identity or characteristic of a chemical/biological species byexposing an emissive species to an electromagnetic radiation spectrumgenerated by a source of electromagnetic radiation and having a rangethat spans greater than or equal to 50 nm, the emissive speciesassociated with the chemical/biological species and detecting adetectable emission produced by the emissive species, wherein thedetectable emission, if present, corresponds to the identity orcharacteristic of the chemical/biological species. In some embodiments,the method comprises determining an identity or characteristic of achemical/biological species by combining a first electromagneticradiation signal and a second electromagnetic radiation signal, whereinthe first electromagnetic signal comprises at least a first photonemission coming from an emissive species with an excited state lifetimeless than 10 ns, and a second electromagnetic signal comprising at leasta second photon emission event coming from an emissive species with anexcited state lifetime 10 ns or longer, wherein the excitation eventcomprises an electromagnetic radiation spectrum, wherein a first portionof the electromagnetic radiation spectrum comprises a wavelength ofbetween 425 nm and 475 nm, and wherein a second portion of theelectromagnetic radiation spectrum comprises a wavelength of between 525nm and 725 nm.

In many instances in which images are obtained (one example is taking aphoto with a cellphone), a single image is not simply obtained at onemoment in time, but portions of the single image are taken at differenttimes (although over a very short time span) to construct the singleimage. For example, one portion of the image (for example, the topportion) is obtained at a very slightly different time than anotherportion of the image (for example, the bottom portion). With a cellphonecamera, a “shutter” (e.g., an electronic shutter) may block portions ofthe image from forming at different times depending on location in theimage, so that the entire image is not over-exposed, and at anyparticular time, some portion but not the entire image is beingrecorded, but over time (very short) the entire image is constructed.With knowledge of when specific portions of the image were obtained, onecan identify information about what happened with a subject of thatimage at those two (or more) different times and/or over the entire timeperiod of image formation (or a portion of that time period). Forexample, if a feature of an emissive species (chemical or biologicalspecies, emissive tag, or the like) changes on the timescale of imageformation, then the single image formed may be used to determinesomething about that change(s).

In some embodiments, the shutter is configured to determine the timeover which light is captured by specific light sensors. In someembodiments, the shutter is a mechanical shutters, an electronic (e.g.,digital) shutter, or combinations thereof. In some embodiments, ashutter may affect (e.g., inhibit the passing of light) for allwavelengths of light, or only certain wavelengths of light, or onlyspecific polarizations of light.

In some instances, the electronic hardware component configured toproduce a single image may not necessarily produce an image and mayinstead provide a different output (e.g., electronic signals). Forexample, in some embodiments, embodiments described herein may comprisean electronic hardware component which collects data capable ofgenerating an image (e.g., and which may or may not be used to form animage).

As will be apparent from the description throughout this disclosure, theinvention(s) includes many variations of the above description, notlimited to any particular type of data and/or signal, particular type ofimage, number of images, type of equipment used to obtain an image, etc.

In some embodiments, an article (or packaging material of an article) isassociated with an emissive material comprising an emissive species(e.g., a luminescent species). In some cases, the emissive species hasan emission lifetime of at least 10 nanoseconds (ns). A person ofordinary skill in the art would understand that suitable emissiontimelines may be selected based on the time resolution of the imagesensor. For some image sensors, a suitable lifetime may be on the orderof milliseconds, while for other image sensors, a suitable lifetime maybe on the order of microseconds. Image sensors with faster timeresponses will generally allow for lifetime-based images to be obtainedusing emissive species with shorter lifetimes. In some cases, acharacteristic of an article (e.g., identity, authenticity, age,quality, purity) may be determined by obtaining an image (or series ofimages) comprising time-dependent information related to an emissivespecies. In certain instances, for example, the emission lifetime of anemissive species may be determined from an image (or series of images).Since the emission lifetime of an emissive species may be modified by anumber of factors, including but not limited to binding or proximity toother molecules (e.g., water, oxygen, carbon dioxide, carbon monoxide,carbon dioxide), thermal history, mechanical manipulations, temperature,pH, and radiation exposure, the measured length of the emission lifetime(e.g., the observed emission lifetime, the emission time period) mayprovide information regarding a characteristic of an associated article.In some instances, an emissive material comprising one or more emissivespecies may be used to identify and/or authenticate an associatedarticle.

According to some embodiments, an article (or packaging material of anarticle) is associated with an emissive material comprising an emissivespecies. In some embodiments, the emissive species is a chemical and/orbiological species. In some instances, an excitation component emitsnon-steady-state pulsed and/or modulated electromagnetic radiation, atleast a portion of which is absorbed by the emissive species. In somecases, a pulsed and/or modulated excitation component can havepolarization, or one or more bands of wavelengths. In some cases,multiple excitation components may be used in sequence and/or may beoverlapping in the time they are applied to an article. In certaincases, the absorbed electromagnetic radiation excites one or moreelectrons of the emissive species to a higher energy state. The one ormore excited electrons are generally metastable and may, in some cases,relax to a lower energy state (e.g., the ground state) through emissionof electromagnetic radiation, thermal dissipation (e.g., throughvibrational energy transfer), and/or a chemical reaction. When anexcited electron relaxes by emitting electromagnetic radiation, it mayproduce a detectable emission over a period of time (also referred to asan “emission time period” under the measurement conditions or “emissionlifetime” when referring to the emissive species). In some cases, animage sensor may detect at least a portion of the detectable emission.

In certain cases, an electronic hardware component (e.g., circuitry, oneor more processors) may subsequently generate an image (or series ofimages) comprising a first portion corresponding to a first portion ofthe emission time period and a second portion corresponding to a secondportion of the emission time period. In some embodiments, the imagecomprises a first portion corresponding to a photon emission detectedunder steady-state conditions and a second portion corresponding to aphoton emission detected under non-steady state conditions.

In certain cases, an electronic hardware component may generate an imageby capturing electromagnetic radiation (e.g., visible light or otherlight) from different portions of emissions at a number of differentlifetimes. The sequence and time periods over which the image iscaptured may be variable and in principle may be varied by programing ormodification of the electronic hardware. In this manner, an image (orseries of images) may be used to obtain time-dependent informationregarding the emissive species and/or a characteristic of the article.For example, within the non-steady state component, the photon emissionsignal may vary. The amount to which the non-steady-state photonemission varies may depend, in some embodiments, on the excited statelifetime of the emissive species and the time period over which theimage is collected. Without wishing to be bound by theory and by way ofexample, if the excited state lifetime is equal to or shorter than thetime period over which the image is collected under rolling shutterconditions, then the signal intensity may vary. By collecting differentparts of an image at different time periods in relation to theexcitation component, unique images may be produced. These images may beused to convey information about the article and serve as anauthentication code. As one non-limiting example, an image (or series ofimages) may be used to determine the emission lifetime of the emissivespecies. In some cases, the emission lifetime of an emissive species maybe modified by binding and/or proximity to other molecules (e.g., water,oxygen, carbon dioxide, carbon monoxide), thermal history, mechanicalmanipulation, temperature, pH, radiation exposure, and/or otherenvironmental factors. In some instances, therefore, the particularemission lifetime value may provide information about a characteristicof the associated article (e.g., the presence or absence of a label, acharacteristic of the environment, information about prior chemical,physical, or other exposures). As another non-limiting example, adifference between a property of the first portion of an image and aproperty of the second portion of the image may provide informationabout a characteristic of the article (e.g., the presence or absence ofa label, a characteristic of the environment, information about priorchemical, physical, or other exposures).

A person of ordinary skill in the art would understand that rollingshutter methods are often criticized as producing undesired artifacts,such as wobble, skew, spatial aliasing, and/or temporal aliasing. As aresult, there is interest in having devices that have a more rapid framecapture rate to minimize these artifacts. With a faster frame rate, thetime between recording a signal (reading) each row or column is smaller.However, in systems and methods described herein, a rolling shuttermethod may be leveraged to generate images containing time-dependentinformation about an emissive material comprising an emissive species.For example, a rolling shutter method may enable the use ofconsumer-level electronics to obtain information based on the emissionlifetimes of one or more emissive species even when using a broadbandelectromagnetic radiation source (e.g., a substantially white lightsource) to excite the species. To obtain this information, the excitingelectromagnetic radiation may be pulsed and/or modulated to create anon-steady-state, time-dependent signal from the emissive species. Insome cases, at least one characteristic of a detectable non-steady-stateemission emitted and/or reflected/scattered by an emissive speciesvaries over the image capture time period.

In some embodiments, an image sensor may be associated with anelectronic hardware component (e.g., circuitry, one or more processors)configured to produce an image. In some embodiments, the electronichardware component is configured to produce a single image comprising afirst portion corresponding to a first portion of an emission timeperiod of an emissive species and a second portion corresponding to asecond portion of an emission time period of an emissive species.

In some embodiments, the electronic hardware component is configured toproduce a single image comprising steady-state emission and a secondportion corresponding to a non-steady-state emission of an emissivespecies. In some embodiments, the first portion of the emission timeperiod is entirely distinct from the second portion of the emission timeperiod. In certain other embodiments, the first portion of the emissiontime period at least partially overlaps with the second portion of theemission time period.

In some embodiments, the single image comprises subsequent portionscorresponding to multiple other emission time periods (e.g., over whicha non-steady state emission signal can be detected). The single imagemay, according to some embodiments, comprise at least 2, at least 3, atleast 5, at least 10, or at least 20 portions, each corresponding to adifferent portion of the emission time period or a different emissiontime period. In some embodiments, the single image comprises 2-5portions, 2-10 portions, 2-20 portions, 5-10 portions, 5-20 portions, or10-20 portions. In some instances, the electronic hardware componentconfigured to produce a single image may not necessarily produce animage and may instead provide a different output (e.g., electronicsignals).

In some embodiments, the image sensor and/or electronic hardwarecomponent are incorporated into a camera (e.g., a digital camera) and/ora phone (e.g., a smartphone). In some embodiments, the camera and/orphone comprises a plurality of image sensors configured to detectelectromagnetic radiation (e.g., emitted and/or reflectedelectromagnetic radiation). In certain instances, the camera and/orphone comprises one or more additional sensors (e.g., sensors configuredto sense an individual's location and/or habits, sensors configured tosense light, acoustics, and/or magnetic fields). In some cases, thecamera and/or phone may be used for mobile spectroscopy applications.

In an exemplary embodiment, a system is provided comprising anexcitation component configured to excite a chemical or biologicalspecies, such that an emission produced by the chemical or biologicalspecies produces a detectable signal, an image sensor configured tosense the detectable signal, wherein the detectable signal comprises atime-dependent emission signal, and an electronic hardware componentconfigured to convert the collected emission into a single image,wherein the single image includes the time-dependent emission signal.

In another exemplary embodiment, a method is provided for identifying achange in a chemical or biological species over a period of time,comprising stimulating the species such that it produces a detectableemission with an excited state lifetime greater than 10 nanoseconds,obtaining, using an image sensor, a single image of the detectableemission, wherein a first portion of the single image corresponds to afirst time period after stimulating the species (e.g., comprising asteady-state photon emission, comprising a non-steady-state photonemission), and wherein a second portion of the single image correspondsto a second time period after stimulating the species, different thanthe first time period (e.g., comprising a non-steady-state photonemission), and determining, based upon a difference between the firstportion and the second portion of the single image, the change in thechemical or biological species.

In another exemplary embodiment, a method is provided for identifying acharacteristic of a chemical or biological species, comprising,stimulating the species such that the species produces a detectableemission with an excited state lifetime greater than 10 nanoseconds,obtaining, using an image sensor, a single image of the detectableemission, wherein a first portion of the single image corresponds to afirst time period after stimulating the species, and wherein a secondportion of the single image corresponds to a second time period afterstimulating the species, different than the first time period, anddetermining, based upon a difference between the first portion and thesecond portion of the single image, the characteristic of the species.In some embodiments, a first portion of the single image corresponds tosteady-state photon emission, and a second portion of the single imagecorresponds to a non-steady-state photon emission, different than thefirst steady-state photon emission. In some embodiments data fromnon-steady-state photon emission can produce multiple other portions ofa single image, and determining, based upon a difference between thedifferent potions the single image, the characteristic of the species.

In yet another exemplary embodiment, a method is provided foridentifying a characteristic of an article, comprising positioning animage sensor proximate an article suspected of containing a chemicaltag, stimulating the article such that the chemical tag, if present,produces a detectable emission, obtaining, using the image sensor, asingle image of the detectable emission, wherein a first portion of thesingle image corresponds to a first time period after stimulating theanalyte, and wherein a second portion of the single image corresponds toa second time period after stimulating the analyte, different than thefirst time period and determining, based upon a difference between thefirst portion and the second portion of the single image, thecharacteristic of the article.

In an exemplary embodiment, a method for detecting the presence of astimulus is provided, comprising exposing an article comprising achemical tag to a set of conditions comprising the stimulus, wherein thechemical tag undergoes a chemical and/or biological reaction and/orassociation in the presence of the stimulus, positioning an image sensorproximate the article, obtaining, using the image sensor, a single imageof a portion of the article comprising the chemical tag, wherein a firstportion of the single image corresponds to a first time period afterexposing the article, and wherein a second portion of the single imagecorresponds to a second time period after exposing the article,different than the first time period and determining, based upon adifference between the first portion and the second portion of thesingle image, the characteristic of the article. In some embodiments, afirst portion of the single image corresponds to steady-state photonemission, and a second portion of the single image corresponds to anon-steady-state photon emission, different than the first steady-statephoton emission. In some embodiments, data from non-steady-state photonemission can produce multiple other portions of a single image, anddetermining, based upon a difference between the different potions thesingle image, the characteristic of the species. In other embodiments,multiple images can be collected under similar of different conditionsto detect additional non-steady-state photon emission data thatdetermine the characteristic of the article.

In another exemplary embodiment, a system is provided, the systemconfigured for identification of a characteristic of an article,comprising a chemical tag associated with the article, the chemical tagcapable of generating a detectable emission having an excited statelifetime more than 10 nanoseconds under a set of conditions, an imagesensor configured to collect an emission produced by the chemical tag,an electronic hardware component configured to convert the collectedemission into a single image, and a source configured to stimulate thechemical tag under the set of conditions, wherein the single imagecomprises a first portion and a second portion, wherein the secondportion is obtained at a different time (and/or under non-steady-stateconditions that are different) than the first portion obtained bystimulation of the chemical tag by the source, and wherein a differencebetween a property of the first portion and the second portion isassociated with a characteristic of the article.

In yet another exemplary embodiment, a system configured foridentification of a characteristic of a chemical tag is provided, thesystem comprising a chemical tag capable of generating a detectableemission having an excited state lifetime more than 10 nanoseconds undera set of conditions, an image sensor configured to collect an emissionproduced by the chemical tag, an electronic hardware componentconfigured to convert the collected emission into a single image, and asource configured to stimulate the chemical tag, wherein the singleimage comprises a first portion and a second portion, wherein the secondportion is obtained under different conditions and/or at a differenttime than the first portion after stimulation of the chemical tag by thesource, and wherein a difference between a property of the first portionand the second portion is associated with a characteristic of thechemical tag. In other cases, images may be produced by combining athird, fourth, fifth, and sixth portion to the first and second portion.The number of portions may be higher yet and will be related to thedesired level of complexity needed for the application at hand.Additionally, in a given reading of an article, it may be that only asubset of the potential emissive species are read as a result of theirselective excitation, physical location, orientation, environment,orientation, lifetime, etc. It may be that with multiple readings of anarticle, different methods are used for each sequential reading.

In some exemplary embodiments, stimulation comprises electromagneticradiation that is provided as a single pulse, a periodic pulse, asequence of pulses, a continuously varying intensity, or combinationsthereof. In some embodiments, a single pulse, a periodic pulse, asequence of pulses, a continuously varying intensity, or combinationsthereof are provided in addition to a constant stimulation ofelectromagnetic radiation. Exemplary pulse durations and pulse rates aredescribed in more detail, below.

In some exemplary embodiments, stimulation comprises electromagneticradiation of discrete wavelength ranges that excite select emissivespecies.

In some exemplary embodiments, stimulation is performed by a flash froma smartphone or camera, is modulated by a shutter, an electronic signal,refractory material, optical modular, mirror, or light valve, and/or isperformed by fluorescent or LED lights.

In some exemplary embodiments, a characteristic is extracted from theanalysis of a number of images taken with different excitations, and/oris extracted from collecting one or more images at different angles,distances, or orientations.

In some exemplary embodiments, the species is associated with apackaging component.

In some exemplary embodiments, the species undergoes a chemical and/orbiological reaction upon stimulating the species.

In some exemplary embodiments, exposure to an analyte causes a changeintensity of an emissive species and/or a change in the lifetime of aspecies with an excited state lifetime longer than 10 nanoseconds.

In some exemplary embodiments, a second stimulation causes a loss ofemission or blockage of first stimulation of one or more emissivespecies contained within an object.

In some exemplary embodiments, a second simulation includes thegeneration of a color or change in absorption and/or emission.

In some exemplary embodiments, combinations of different first, secondand additional stimulations can cause changes in the images that areacquired over the course of 100 nanoseconds to 100 milliseconds.

In some exemplary embodiments, the chemical tag undergoes a chemicaland/or biological reaction upon stimulating the article, and/orstimulating the article comprises producing a chemical and/or biologicalreaction in the chemical tag.

In some exemplary embodiments, the chemical tag comprises at least oneemissive dye having an excited state lifetime more than 10 nanoseconds.

In some exemplary embodiments, a rolling shutter component is associatedwith the image sensor.

In some exemplary embodiments, the chemical tag produces a detectableemission having an excited state lifetime more than 10 nanoseconds inthe presence of the stimulus.

In some embodiments, lifetimes associated with different emissivematerials as well as their other characteristics are used generateinformation. For example, the combination of images (or signals) takenunder constant static illumination and/or those taken a time periodafter a flash of white light, or taken during a series of rapid flashes,or acquired during a continuously varying light intensity at one or morefrequencies, can differentiate specific signals in the presence ofcomplex or cluttered backgrounds. In some embodiments, light acquiredwhile the emissive materials are excited by a constant intensity lightsource is referred to as steady-state photon emission. Without wishingto be bound by theory, in some embodiments, an emissive material will beactivated in the steady-state photon emission process. In embodiments inwhich a detectable signal is acquired after the exciting source ofelectromagnetic radiation has been removed, or while the excitation isvaried by pulsing, or by continuous modulation in intensity atfrequencies similar to the rate at which the images are acquired by therolling shutter, are referred to as non-steady-state photon emissionevents. For example, the materials associated with non-steady-statephoton emission events generally have excited stated lifetimes longerthen 10 nanoseconds.

In some embodiments, the time domains at which the exciting light isvaried in non-steady-state photon emission events is in some caseswithin a factor of 10 (longer or shorter) than the time over which theimage is collected. In some embodiments, however, the time is within afactor of 10 (longer or shorter) than the time over which the image iscollected. In some embodiments, the time is within a factor of 100(longer or shorter) than the time over which the image is collected. Insome embodiments, the time is within a factor of 1,000 (longer orshorter) than the time over which the image is collected.

Advantageously, in some embodiments, the systems, compositions, andmethods described herein may be used in conjunction with consumerelectronics without further modification for the detection,identification, authentication, and/or characterization of achemical/biological species (or an article with which thechemical/biological species is associated). For example, digitalcameras, such as those incorporated into consumer electronics including,for example, smartphones, generally rely on light emitting diode (LED)source(s) designed to illuminate objects (e.g., with color balancedlight that approximates natural daylight). Such light is generallyreferred to as white light. Advantageously, the use of white light inconsumer electronics generally allows for recording of images that havesubstantially the same color balance as would be expected from naturallight illumination. However, while the description herein generallyrefers to sources of electromagnetic radiation associated with consumerelectronics, those of ordinary skill in the art would understand, basedupon the teachings of this specifications, that other types of whitelight sources are possible. For example, the interior spaces ofbuildings are, in some cases, illuminated with white light sources. Insome embodiments, a white light source is modulated and/or flickering atfrequencies that are not generally detectable by the human eye. In somesuch embodiments, can provide a non-steady state excitation to anarticle. Advantageously, the systems, compositions, and methodsdescribed herein may be configured, in some embodiments, to utilize suchubiquitous white light sources (e.g., without the need for additionalfilters or components, in some embodiments). In some embodiments, suchsources of electromagnetic radiation may be used to excite an emissivematerial(s).

The embodiments described herein are generally useful (e.g., using whitelight excitable materials as emissive elements), for example in,chemical sensing, biological sensing, environmental sensing, thermalexposure evaluation, light exposure, humidity exposure, radiationexposure, physical alterations, and/or product authentication. In anexemplary set of embodiments, the response of one or more emissivespecies may be captured by a consumer electronic device. In someembodiments, the consumer electronic device is a smartphone comprising adigital camera, (e.g., which functions as the reader and/or sensor). Insome embodiments, the consumer electronic device comprises both a sourceof electromagnetic radiation for, and a sensor capable of detecting anemission from, one or more emissive species (e.g., a white lightexcitable emissive species).

Although smartphones are generally described herein as an exemplaryconsumer electronic device, those of ordinary skill in the art wouldunderstand, based upon the teachings of this specification, that otherconsumer electronic devices are also possible and/or the individualcomponents that generally make up a consumer electronic device such as asmartphone's image capture electronics and/or associated light sourcemay be used without the consumer electronic device. For example, thesource of electromagnetic radiation (e.g., configured to generate whitelight) may be, in some cases, a white light excitation source (e.g., alight emitting diode (LED) not physically integrated into a consumerelectronic device. In some embodiments, the source of electromagneticradiation is a component integrated in a consumer electronic device. Insome embodiments, the source of electromagnetic radiation is an externalcomponent to the consumer electronic device. Non-limiting examples ofsuitable sources of electromagnetic radiation include a flash, aflashlight, a torch, LEDs, optical fibers, lasers, ultraviolet-visiblelamps (e.g., deuterium, tungsten halogen), incandescent bulbs, or thelike. As described above and herein, advantageously and in someembodiments, use of the systems described herein may involve the use ofan unmodified consumer electronic device such as a smartphone (ortablet, computer, digital camera, or the like) that when equipped withan application program (app), is used to excite an emissive species(i.e. emitter) and may also be used to read information derived from anyresulting photon emission events (e.g., events that vary in wavelengthand/or time). In some embodiments, such emission events (e.g., photonemissions) may convey important information such as the presence orabsence of chemicals of interest, results of biological diagnosticassays, the quality of objects by detecting their cumulative thermal oroptical exposure, evidence of physical manipulation, the presence ofmolecules of interest, and/or the products authenticity. In someembodiments of this invention, this information may be read in thepresence of a complex background environment (e.g., comprising one ormore sources of stray light in addition to the source of electromagneticradiation). In some cases, it may be advantageous to read the photonemissions in a way that excludes all other sources of stray light.

As will be apparent from the description throughout this disclosure, theinvention(s) includes many variations of the above description, notlimited to any particular type of consumer electronic, source ofelectromagnetic radiation, sensor (e.g., CMOS sensor), etc.

In some embodiments, one or more of the electronic hardware componentsdescribed herein comprises a controller and/or (micro)processor. In someembodiments, the controller is configured (e.g., programmed) to receiveand transmit data commands to/from one or more components of thecomponent and/or the smartphone (or other consumer electronic device).In some embodiments, the data includes one or more signals from one ormore sensors. In some embodiments, the controller may be configured toadjust various parameters based on external metrics. For example, insome embodiments, the controller is configured adjust the wavelength ofelectromagnetic radiation, pulse, frequency, operation of the source ofelectromagnetic radiation, etc. in response to a signal from a sensor inelectrical communication with the controller. In some embodiments, thecontroller adjusts the wavelength of electromagnetic radiation, pulse,frequency, operation of the source of electromagnetic radiation, etc. inresponse to an input from the user and/or a signal from the sensor.

The embodiments described herein can be implemented in any of numerousways. For example, the embodiments may be implemented by any suitabletype of analog and/or digital circuitry. In some embodiments, theembodiments may be implemented using hardware or a combination ofhardware and software. When implemented using software, suitablesoftware code can be executed on processing circuitry including anysuitable processor (e.g., a microprocessor) or collection of processors,whether provided in a single computer or distributed among multiplecomputers (or other consumer electronic devices). It should beappreciated that any component or collection of components that performthe functions described above can be generically considered as one ormore controllers that control the above-discussed functions. The one ormore controllers can be implemented in numerous ways, such as withdedicated hardware or with one or more processors programmed usingmicrocode or software to perform the functions recited above. The one ormore embodiments can be implemented in numerous ways, such as withdedicated hardware, or with general purpose hardware (e.g., one or moreprocessors) that is programmed using microcode or software to performthe functions recited above.

In some embodiments, the embodiments described herein comprise wirelesscapabilities for enabling suitable communication with otherdevices/systems (e.g., for controlling aspects of the electroniccomponent(s), controlling a source of electromagnetic radiation,controlling a sensor or other component). Wireless devices are generallyknown in the art and may include, in some cases, LTE, WiFi and/orBluetooth systems. In some embodiments, the systems and/or devicesdescribed herein comprise such a wireless device.

In some embodiments, the embodiments described herein may be configuredto adjust various parameters based on external metrics. For example, insome embodiments, the system is configured to adjust the rate,wavelength, pulse, modulation, intensity, etc. of electromagneticradiation from the source of electromagnetic radiation (e.g., inresponse to a signal from a sensor and/or consumer electronic device inelectrical or wireless communication with and/or associated with thesystem). In some embodiments, the system adjusts the rate, wavelength,pulse, modulation, intensity, etc. of electromagnetic radiation from thesource of electromagnetic radiation in response to an input from theuser and/or a signal from the sensor and/or consumer electronic device.

In some embodiments, the system is associated with and/or comprises apower source. The power source may include any appropriate material(s),such as one or more batteries, photovoltaic cells, etc. Non-limitingexamples of suitable batteries include Li-polymer (e.g., with between100 and 1000 mAh of battery life), Li-ion, nickel cadmium, nickel metalhydride, silver oxide, or the like. In some cases, the battery may applya voltage (e.g., to a degradable material as described herein) inresponse to a physiological and/or external metric and/or signal (e.g.,by a user). For example, the voltage may be used to trigger the exit ofthe resident structure by e.g., applying a voltage to thermallysensitive degradable component as described herein. For example, theaverage magnitude of the voltage applied to the degradable component(s)may be between 0.001 to 0.01 V, between 0.01 to 0.1 V, between 0.1 V and10.0 V, between 1.0 V and 8.0 V, between 2.0 V and 5.0 V, between 0.1 Vand 5.0 V, between 0.1 V and 1.5 V, between 0.1 V and 1.0 V, between 1.0V and 3.0 V, between 3.0 V and 8.0 V, or any other appropriate range.

Any electronic component circuitry may be implemented by any suitabletype of analog and/or digital circuitry. For example, the electroniccomponent circuitry may be implemented using hardware or a combinationof hardware and software. When implemented using software, suitablesoftware code can be executed on any suitable processor (e.g., amicroprocessor) or collection of processors. The one or more electroniccomponents can be implemented in numerous ways, such as with dedicatedhardware, or with general purpose hardware (e.g., one or moreprocessors) that is programmed using microcode or software to performthe functions recited above.

In this respect, it should be appreciated that one implementation of theembodiments described herein comprises at least one computer-readablestorage medium (e.g., RAM, ROM, EEPROM, flash memory or other memorytechnology, or other tangible, non-transitory computer-readable storagemedium) encoded with a computer program (i.e., a plurality of executableinstructions) that, when executed on one or more processors, performsthe above-discussed functions of one or more embodiments. In addition,it should be appreciated that the reference to a computer program which,when executed, performs any of the above-discussed functions, is notlimited to an application program running on a host computer. Rather,the terms computer program and software are used herein in a genericsense to reference any type of computer code (e.g., applicationsoftware, firmware, microcode, or any other form of computerinstruction) that can be employed to program one or more processors toimplement aspects of the techniques discussed herein.

In some embodiments, the systems and devices described herein compriseone or more optical detectors such as photodetectors (also referred toas “photosensors” or “photodetection elements”) and may include anycomponent that converts light or other electromagnetic radiation into anelectrical signal (e.g., current, voltage). Non-limiting examples ofsuitable photodetectors include phototransitors and photodiodes.Non-limiting examples of image sensor arrays (which includephotodetectors) include charge-coupled device (CCD) arrays andcomplementary metal oxide semiconductor (CMOS) arrays.

By way of example, smartphones currently generally leverage CMOS basedoptical detectors (imaging chips) to detect light. The sensitivity (ISO)of these chips and the time periods over which they collect light(exposure time) may vary, with these functions typically performedautomatically by a smartphone (or other consumer electronic device) whentaking a photograph. The speed by which the optical detection systemacquires an image is generally referred to as the shutter speed. Inprevious film-based cameras the shutter was a physical device, whereasin smartphones the camera's shutter is typically electronic in nature.One exemplary method of producing an electronic shutter event isgenerally referred to as a rolling shutter because the image collectionis accomplished by reading the output of different rows, or columns, ofphoto-detection elements in series. As a result of the manner in whichthese signals are accumulated, there may, in some cases, be a slighttime delay between the reading of sequential rows (or columns) duringacquisition of the image. In some embodiments, this time-encoded signalmay provide information to identify a characteristic of an emissivespecies (or an article associated with an emissive species).

Another exemplary method of producing an electronic shutter is generallyreferred to as a global shutter. This method may also be used, forexample, to capture non-steady-state photon emission information if thecycle time of the image collection method is configured to capture dataat different time points of the emission lifetime.

Advantageously, embodiments described herein leverage the time delay andthe ability to produce composite information by using emissive elementsthat give off light at characteristic rates and produce information thatcan be captured by the time delay associated with image acquisitionusing the rolling shutter mechanism.

An image is a collection of one or more pixels from the detection systemand the ability to see patterns through collections of pixels or tosignal average by using multiple pixel outputs will be used in someembodiments of this disclosure. In these methods images can be acquiredat the same time as the light is exciting the emissive species andcombined with images that are acquired after the illumination has beenremoved or has changed in intensity. Some photons resulting fromreflected or scattered light will be observable with concurrentillumination, and the light source can be ambient in nature. In manyinstances in which images are obtained (one example is taking a photowith a smartphone), a single image is not simply obtained at one momentin time, but portions of the single image are taken at different times(although over a very short time span) to construct the single image.For example, one portion of the image (for example, the top portion) isobtained at a very slightly different time than another portion of theimage (for example, the bottom portion). With a smartphone (or otherconsumer electronic device) camera, a “shutter” (e.g., an electronicshutter) may block portions of the image from forming at different timesdepending on location in the image, so that the entire image is notover-exposed, and at any particular time, some portion but not theentire image is being recorded, but over time (very short) the entireimage is constructed. With knowledge of when specific portions of theimage were obtained, one can identify information about what happenedwith a subject of that image at those two (or more) different timesand/or over the entire time period of image formation (or a portion ofthat time period). For example, if a feature of an emissive species(chemical or biological species, emissive tag, or the like) changes onthe timescale of image formation, then the single image formed may beused to determine something about that change(s). In some embodiments,an entire image (or images) comprise a considerable amount of data thatis not relevant to the signals of interest and that analysis may dependon a select number of pixels. In some such embodiments, a select featureor number of pixels may constitute the image and/or information from themeasurement. In some embodiments, pixels are combined to produce datathat represents the spatial distribution of a signal. For example, animage may reveal a vertical line of signal with regards to a horizontaldirection. In some embodiments, the vertical and horizontal are relativedirections and not generally absolute. The spatial patterning of thedifferent emissive species can inform a device on how to computationallyanalyze the information collected. In some embodiments, analysis of thesignal may comprise a sum of the intensity of the pixels along thevertical direction. In some embodiments, a plot of these summedintensities in the horizontal dimension provides a method to analyze thetotal intensity of the line relative to the background. Such an analysisin concert with calibration signals may be used, in some cases, toproduce quantitative measurements.

Advantageously, photons from scattered and reflected light can beintensified when illuminated with a white light source. In the casewhere there is no stray (background or ambient) light; no image will bedetected from materials that are purely reflective or scattering whenthe excitation light is turned off. When a white light excitable emitterwith an excited state lifetime of similar magnitude to the rate at whichthe image is acquired by sequential reading of individual rows orcolumns of optical detectors as performed by the rolling shutter, it ispossible to extract information from the resulting image (e.g., providedthat the excitation is not in a steady-state mode). These longer-livedsignals persist after the excitation light is removed and the timescaleover which the photon emission occurs is related to the excited statelifetime of the material. For a modulated non-steady-state excitation,longer-lived signals may, in some cases, provide a phase shift in thephase of the photon emission associated with the longer-lived species.

As will be apparent from the description throughout this disclosure, theinvention(s) includes many variations of the above description, notlimited to any particular type of image, number of images, type ofequipment used to obtain an image, etc.

The methods in this invention detect light emitted that ischaracteristic of an article. For example, a first portion of theemitted light may be, in some embodiments, reflected or scattered lightthat is not absorbed by the article and a second portion of the emittedlight that is absorbed may be dissipated as heat or create an excitedstate that can emit a photon at a characteristic rate. The emitted lightmay be measured, in some cases, at the same time as a constant intensityexcitation is applied (e.g., such that the stationary signal is asteady-state photon emission event). In some embodiments, if a timecomponent is present in the excitation relative to the collection of theemitted light, a non-steady-state emission is produced. The timecomponent may be, for example, a time modulation of the excitationintensity at all or different wavelengths, time dependent changes inpolarization, or a delay after the excitation light is removed. In someembodiments, an article is associated with an emissive materialcomprising an emissive species. In some cases, the emissive species hasan emission lifetime as described herein. A person of ordinary skill inthe art would understand that suitable emission timelines may beselected, for example, based on the time resolution of the image sensor.For some image sensors, a suitable lifetime may be on the order ofmilliseconds, while for other image sensors, a suitable lifetime may beon the order of microseconds. For example, image sensors with fastertime responses will generally allow for lifetime-based images to beobtained using emissive species with shorter excited state lifetimes. Insome cases, a characteristic of an emissive species (e.g., identity,authenticity, age, quality, purity, presence) may be determined byobtaining an image (or series of images) comprising time-dependentinformation related to an emissive species. In certain instances, forexample, the emission lifetime of an emissive species may be determinedfrom an image (or series of images). Since the emission lifetime of anemissive species may be modified by a number of factors, including butnot limited to binding or proximity to other molecules (e.g., water,oxygen, carbon monoxide), physical alteration, temperature, pH, andradiation exposure, the measured length of the emission lifetime (e.g.,the observed emission lifetime, the emission time period) may provideinformation regarding a characteristic of an associated article. In someinstances, an emissive material comprising one or more emissive speciesmay be used to identify and/or authenticate an associated article.However, in some embodiments, the system need not produce an image. Forexample, data collected from a sensor may be used to provide informationcorresponding to a characteristic/identity of an emissive species, asdescribed herein.

In some embodiments, a shutter mechanism is used that can provide timeresolution using what is referred to as the rolling shutter, which isused in many smartphones and digital cameras. This non-steady-statephoton emission data/image may be combined, in some embodiments, withsteady-state photon emission data/image to provide a characteristicabout an article. The rolling shutter is generally an electronicmechanism and is related to the electronic reading of the imaging chip.Similar to a classical shutter used in older cameras, the rate overwhich the chips are read may be varied. In smartphones or digitalcameras a chip detects the light projected onto it by sequentiallyreading rows or columns of the photo-detection elements in rapidsuccession. The time delay with this reading allows for the device tobehave in a way that can extract information as a function of thelifetime of the emissive species. This information may be extracted froma single image by reading the different rows or columns or could beextracted from the overlay of many images collected with different typesof excitation and rolling shutter reading conditions. For example, it ispossible that an excitation wherein the intensity changes with time maybe used in conjunction with a rolling shutter to acquire lifetime data.In some embodiments, the rates at which the excitations are modulatedmay vary over a large range and will ideally approach similar cycleperiods in time to the excited state lifetimes of the different emissivespecies. By varying the rates of image collection (rolling shutter)rates and the excitation conditions, it is possible, in someembodiments, to selectively detect different emissive species andminimize background signals. It is also noteworthy that this methodallows for the selective detection of multiple different species havingdifferent excited state lifetimes within a biological assay. In someembodiments, images and/or data are collected such that information isproduced by analysis of both steady-state photon emission events andnon-steady-state photon emission events. This feature may be combinedwith the chromaticity (wavelengths) of the emissive species as well asmethods that use polarization of light to decrease optical noise. Insome embodiments the reader is a conventional smartphone that uses arolling shutter. An aspect of the smartphone is the timing between theexcitation and the speed of the rolling shutter. An excitation may bepulsed and entire images collected after a single pulse. Alternatively,the excitation may be pulsed multiple times during the collection of asingle image. Additionally, the excitation may be continuously modulatedat one or more varying frequencies throughout the collection of theimages using the rolling shutter mechanism. It is also possible that aseries of images may be determined that have combinations of differentexcitation frequencies and rolling shutter speeds. In some cases, areader will initially collect data under many different excitationconditions and rolling shutter conditions. Computational methods may beused to determine which combination of these trial excitation androlling shutter conditions produces the superior signal. This signal maybe extracted or the reader can make additional measurements under theoptimal conditions. By way of example to illustrate this concept, if asingle analysis (or trial measurement) takes 10 milliseconds, it ispossible to make 100 separate measurements in a second. In these waysthe smartphone, digital camera, or detection device (reader) mayadvantageously be used to selectively detect signals with particularlifetimes in a complex background. For example, under some conditionsthe devices may be used to detect delayed-phosphorescence to the largeexclusion of delayed-fluorescence, prompt-phosphorescence, andcolorimetric signals. Alternatively, under other conditions the devicesmay be used to preferentially detect delayed-fluorescence andprompt-phosphorescence over delayed-phosphorescence and colorimetricsignals. However, it is clear that these selective detection events,although useful in their own right, are advantageously greatly enhancedwhen used in conjunction with other images that contains additionalinformation. For example, pairwise combinations of any of the imageanalysis techniques described herein may be used. Multiple images (e.g.,from steady-state and non-steady-state photon emission events) may befused that are collected for the detection of any of the signals. Insome contexts, the use of multiple images (and/or data sets) may beconsidered as signal averaging, which generally increases the signal tonoise ratio at a rate equal to the square root of the number of signalsaveraged. In some embodiments, the combination of optical images thatvary in wavelength and lifetime allows information to be extractedand/or encoded. When an article is being optically excited, emission(s)may be detected, in some embodiments, that are comprised of reflectedphotons and those resulting from the relaxation of excited state(s)generated by the optical excitation. For example, if the exciting lightis of constant intensity, the emission may be invariant while theexciting light is on. Such a static situation is generally asteady-state photon emission event, as described herein. The color ofthe light in the steady-state mode will generally be a combination ofthat generated by what is generally referred to as subtractive color andthe colors that are emitted by the relaxation of the excited states ofthe emissive material. Without wishing to be bound by theory,subtractive color is generally the result of certain wavelengths beingabsorbed by a material and some or all of the excited state relaxing toa ground state by a thermal mechanism. In some embodiments, theconversion of light to heat results in increased emission in theinfrared region of the electromagnetic spectrum, but not at wavelengthsdetected by a CMOS imaging system.

In some cases, when the exciting light is turned off, the only reflectedlight may be caused by ambient stray light. In some embodiments straylight will be present. In an exemplary set of embodiments, it isadvantageous to prevent stray light and eliminate substantially allforms of reflected light.

In some embodiments, images (or the equivalent) collected with varyingexcitation, or after an exciting light source has been removed (turnedoff), may vary in intensity as a function of time and are generallynon-steady-state photon emission events. Generally, excited emissivematerials that have excited state lifetimes <10 nanoseconds (ns) willalso not be efficiently detected with CMOS imaging methods e.g., afteran exciting light source has been turned off. Without wishing to bebound by theory, this is a result of the rolling shutter mechanism beingunable to efficiently capture light within 10 ns of a light source beingturned off. In some embodiments, emissive species that have lifetimes<10 ns are said to display prompt fluorescence and may be detected assteady-state photon emission events. Longer-lived emissive species may,in some cases, however be detected by a CMOS imaging system after thelight source has been turned off and are generally non-steady-statephoton emission events. There are multiple types of suitable materialsthat display longer lived emissions that can be detected asnon-steady-state photon emission events, in accordance with theembodiments described herein. By way of example, and without wishing tobe limited as such, with a continuously modulated excitation sourcescattering/reflection/prompt-fluorescence and non-steady-state photonemissions may be present throughout the measurement, however thescattering/reflection/prompt-fluorescence photon emission may have thesame modulated waveform as the modulated excitation and thenon-steady-state may have differences in the waveform of its modulatedemission that reflect a delay in the photons being emitted relative tothe excitation. The waveforms from modulated emissions need notnecessarily be detected directly, but may produce features in an imagecollected over a time period by, for example, a rolling shuttermechanism.

For example, materials that exhibit delayed-emission include systemsthat undergo what is generally referred to as thermally activateddelayed fluorescence (TADF). These materials generally have a singlet(electron spins aligned antiparallel) and triplet (electron spinsaligned parallel) excited states that are very close in energy. Withoutwishing to be bound by theory, when the energy separating these statesis small enough, they are in thermal equilibrium and in this equilibriumthe electron spins may flip by a spin-orbit coupling mechanism. In thecase that there are no heavy atoms that are capable of providing thelarge spin-orbit coupling necessary for efficient emissive relaxationfrom the excited state triplet directly to the ground state singlet, thetriplet state may be said to be very weakly emissive, or in asubstantially dark state. The triplet state is generally lower in energythan the singlet state and hence the equilibrium population of thisstate will be higher than the singlet state. However, when the excitedstate is in the singlet electronic configuration, the emissiverelaxation to the ground state is efficient. As a result, the delay inthe emission is the result of the excited state spending a portion oftime in the dark triplet state.

Other methods for the generation of delayed fluorescence include the useof twisted charge transfer excited states and systems wherein othermetastable charge-separated states are produced that may recombine togenerate an excited singlet electronic state in an emissive material.

In some embodiments, the TADF process can occur within a singlemolecule. In some such embodiments, π-conjugated organic moleculegenerally has substitution patterns of electron-donating and electronaccepting groups. Certain patterns of molecules can allow for thehighest occupied molecular orbital (HOMO) to have a special distributionover the molecule that has low overlap with the lowest unoccupiedmolecular orbital (LUMO). The molecule can be excited with light and itwill rapidly thermally equilibrate to the lowest energy excited singletstate. In some cases, there is one electron occupying an orbital thatresembles the original HOMO and one electron occupying an orbital thatresembles the original LUMO. Without wishing to be bound by theory, thelow orbital overlap between these two electrons results in the tripletstate being very close in energy to the singlet. This energy proximitygenerally can allow for thermal interconversion between the singlet andtriplet states, which is responsible for the TADF effect.

An alternative approach, in some embodiments, to create a TADF system isto bring two separate molecules together. In some such embodiments, oneof the molecules behaves as an electron donor and the other behaves asan electron acceptor. If they are placed relative to each other suchthat their π-orbitals can interact, then the donor molecule may donate asmall amount of its electron density to the acceptor molecule. Such aninteraction is generally said to be a ground-state charge-transfercomplex. In some embodiments, the HOMO is on the donor molecule and theLUMO is on the acceptor molecule. Upon absorption of a photon thecharge-transfer may be greatly enhanced and it is often approximated, insome cases, that an electron from the donor transfers to the acceptor.The excited-state complex formed with such a photon absorption isgenerally referred to as an exciplex. Without wishing to be bound bytheory, the excited-state has two half-filled orbitals, with one orbitalresembling the original HOMO of the donor molecule and the other orbitalthe resembles the original LUMO of the acceptor molecule. This situationgenerally results in low overlap between the two half-filled orbitals,which results in a small energy difference between the singlet andtriplet excited states. For example, the small energy separation of thesinglet and triplet states of the exciplex allows for theirequilibration, and is generally responsible for the TADF effect.

In some embodiments, the lifetimes of efficient TADF emitters are longerthan 10 ns and less than 50 microseconds (e.g., 10 ns to 20 ns, 10 ns to50 ns, 10 ns to 100 ns, 10 ns to 500 ns, 10 ns to 1 μs, 10 ns to 5 μs,10 ns to 10 μs, 10 ns to 50 μs, 10 ns to 100 μs, 10 ns to 500 μs, 10 nsto 1 ms, 10 ns to 5 ms, 10 ns to 10 ms, 10 ns to 50 ms, 10 ns to 100 ms,10 ns to 500 ms, 10 ns to 1 s, 10 ns to 5 s, 10 ns to 10 s, 50 ns to 100ns, 50 ns to 500 ns, 50 ns to 1 μs, 50 ns to 5 μs, 50 ns to 10 μs, 50 nsto 50 μs), although longer lifetimes are possible. In general, andwithout wishing to be bound by theory, shorter lifetimes correspond tohigher emissive quantum yields. For example, competing non-radiativerelaxation processes may result in conversion of the excited state tothe ground state without emission of an optical photon. The emissionefficiency, generally referred to as the quantum yield, is related tothe ratio of the radiative rate to all of the radiative andnon-radiative relaxation rates. For example, if the emission lifetime isshorter, this can result in the radiative rate being the dominatedeactivation process. As a result, a time domain of 10 ns to 50microseconds (or longer) is the approximate lifetime over whichmaterials with more efficient emissions will be observed. Longerlifetimes indicate that the materials are spending more time in thenon-emissive triplet state and non-emissive processes can dominate. Theequilibrium between the singlet and triplet states may depend, in someembodiments, on the environment as well as the intrinsic properties ofthe TADF materials.

Advantageously, a delayed-fluorescent signal generally allows foremissions to be detected after the removal of an exciting light sourcein a non-steady state photon emission event or under modulated lightwherein differences between the waveform of the exciting light and thewaveform associated with the modulated photon emission are present. Oneexemplary advantage of this process is that background emission(s) fromreflection or scattering and prompt fluorescence are not present atlonger lifetimes. In an exemplary set of embodiments, the delayedfluorescent signal can be read by a smartphone (or other consumerelectronic device). For example, the rolling shutter mechanism mayenable image capture to occur over the lifetime of the emission. In someembodiments, the rolling shutter captures the signal decaying from thetime the light is removed and thereby detects the emission in theabsence of the exciting light. The ability to detect signals that aredecaying after the light is removed is generally a non-steady-statemeasurement and the emission is said to be a non-steady-state emission.In some cases, pulsing or continuously modulated light may be used todifferentiate between signals coming from the non-steady state photonemission events and those coming from the steady-state photon emissionevents. In some embodiments, calibration and/or matching of a shutterspeed (exposure time), a sensitivity of the photon detection elements(ISO), and characteristics of the exciting light source (flash withspecific delay, flashing rate, or frequency over which the intensity ismodulated) may be performed. Advantageously, in some embodiments,absolute timing of the light source and reading of the CMOS imaging chipis not needed. For example, the relative rates may be reflected in thedata and analyzed computationally. This latter feature advantageouslyallows for an independent light source that is not electronicallyconnected to the CMOS rolling shutter image acquisition to be used.

In some embodiments, phosphorescent materials with lifetimes over theperiod of 10 ns to 50 microseconds are used. In some such embodiments,these materials are generally referred to as prompt-phosphorescentmaterials. In some embodiments, heavy atoms present in thephosphorescent material, or in its immediate environment, facilitate thespin transition process. In some embodiments, the heavy atoms promotetwo different electron spin interconversion processes. Firstly, they maypromote what is called intersystem crossing by converting the initiallycreated singlet excited-state into a triplet excited-state by a spinorbit coupling mechanism. In some cases, the triplet is sufficientlylower in energy that there is no thermal equilibrium with the singlet.To achieve prompt-phosphorescence, which generally involves the emissiverelaxation of the excited triplet state to the ground singlet state, theheavy atom may, in some cases, produce a mechanism that allows for aspin flip. Without wishing to be bound by theory, this is oftenaccomplished by spin-orbit coupling achieved by electronic coupling tothe heavy atom(s). Non-limiting examples of heavy atoms are elementsheavier than e.g., neon and examples of main group heavy atoms include,but are not limited to, Al, Si, P, S, Cl, Ga, Ge, Sb, Se, Br, In, Sn,Sb, Te, and I. The heavier atoms generally provide for stronger spinorbit coupling and, in some embodiments, by attaching multiple heavyatoms to an organic base chromophore, the efficiency of thephosphorescence may be increased.

Many organometallic (molecules with metal-carbon bonds) andmetallo-organic (molecules wherein the metals are bound to organicligands though elements other than carbon) may, in some embodiments,exhibit prompt-phosphorescence. For example, the bonding may be thoughphosphorous, sulfur, oxygen, or nitrogen groups on the organic ligand.Non-limiting examples of suitable materials having prompt-phosphorescentbehavior include those having metal centers are Cu, Zn, Ru, Rh, Pd, Ag,Cd, Re, Os, Jr, Pt, Au, and Hg. Post transition metal elements includingPb and Bi may also be used in systems displaying prompt-phosphorescence.These materials may also be detected using a smartphone and rollingshutter, in accordance with embodiments described herein. For example,in some embodiments, the rolling shutter mechanism allows for theprompt-phosphorescence emission to be recorded after removal of theexcitation light thought non-steady-state photon emission events.

Another class of material are those displaying emission lifetimes longerthan 50 microseconds that may extend to many seconds (e.g., at least 50μs, at least 100 μs, at least 500 μs, at least 1 ms, at least 5 ms, atleast 10 ms, at least 50 ms, at least 100 ms, at least 500 ms, at least1 s, at least 2 s, at least 3 s, at least 4 s, at least 5 s, at least 6s, at least 7 s, at least 8 s, at least 9 s, or at least 10 s), andthese materials are generally referred to a delayed-phosphorescentemitters. To have significant emission over these times the materialsgenerally comprise very rigid structures that attenuate non-radiativeprocesses and/or have f-block elements wherein the orbitals involved inthe emission are contracted and hence may be influenced minimally by thedynamics of the coordinating ligands. Non-limiting examples of rigidmaterials are ruby structures comprising Cr+3 doped Al2O3 (a ceramicmaterial with a very high melting temperature and excited statelifetimes of 3.4 milliseconds). Other examples include, but are notlimited to, rigid organic molecules in appropriate matrix materials. Forexample, examples of suitable f-block element-based materials areinorganic and metalloorganic materials containing Eu, Tb, Er, and Gd.The rolling shutter mechanism generally allows, in some embodiments, forthe delayed-phosphorescence emission to be recorded to create imagesafter removal of the excitation light from non-steady-state photonemission events.

In some embodiments, a smartphone or a system having similar componentsto a smartphone, is used to read both steady-state and non-steady-statephoton emission events from emissive species described herein. There area number of applications wherein the emission signal may be used e.g.,to indicate the presence of a molecule or biomolecule, determine thethermal history of a material, if a material has been physicallyaltered, the authenticity of a material, if a material has been exposedto ionizing radiation, if a material has been exposed to a chemical orbiological analyte, and/or if a material has been exposed to ultravioletradiation. As described above and herein, the excitation source need notbe part of the smartphone and may be an external source that iscontrolled to produce steady-state and non-steady-state emissivesignals.

However, in an exemplary set of embodiments, the smartphone (or otherconsumer electronic device) does not require augmentation and performsthe necessary excitation to acquire steady-state and/or non-steady-statesignals as a stand-alone system (e.g., with appropriate software). Thecamera function of the smartphone is designed to capture images, andalthough images will be very useful in some applications, the deviceneed not produce an image. Specifically, individual pixels orcollections of pixels can be used to collect the necessary signals toobtain the information of interest. Alternatively, the signal producedby a sensor (e.g., an image sensor) may be read directly without theproduction of pixels and/or an image.

To pair combinations of materials that will produce emissions as aresult of reflection, scattering, prompt-fluorescence,delayed-fluorescence, prompt-phosphorescence, and/ordelayed-phosphorescence that may be excited and read by a smartphone,the characteristics of the light sources (flashes) used in smartphonesmay be considered. In general, most smartphone light sources (LEDs) havetheir highest intensity output around 450 nm and depending on the exactmake and model this peak intensity can be at higher or lowerwavelengths. For example, Apple Corporation's iPhone 11 has a peakintensity very close to 450 nm, but their iPhone X and iPhone 6S modelshave peak light outputs closer to 440 nm. While a Google Pixel 2 Androidsmartphone has its peak light output closer to 460 nm. The light outputof these light sources are finite, but minimal at 400 nm. They alsoexhibit lower intensity outputs that extends beyond 650 nm and in somecases beyond 700 nm. See, for example, FIGS. 17A-17I. The combined totaloutput of a smartphone light source produces light that is perceived tothe human eye to be similar to sunlight and is generally referred to aswhite light.

An exemplary condition to achieve an excited state of a compound byphoton absorption may include excitation photons with an energy equal toor greater than the energy thereby separating the material's groundelectronic state and its first excited electronic state. Anapproximation to this energy, without wishing to be bound by theory, isthe difference in energy between the HOMO and the LUMO of a material.Those of ordinary skill in the art would be capable, based upon theteachings of this specification, to use the computation of HOMO and LUMOlevels to gain valuable insights into materials selection. Those ofordinary kill in the art would be capable of measuring the opticalabsorption spectra of materials to gain valuable insight into materialsselection based upon the teachings of this specification. The efficiencyof excitation of the material by a given light source may depend, forexample, upon the optical absorption characteristics of the absorbingemissive material and the intensity of the light from the exciting lightsource at the same wavelength. The amount of the material excited isgenerally related to the product of these values. Another approximationthat is widely used to understand the characteristics of the absorptionsof materials is generally referred to as the Born Oppenheimerapproximation. One of the tenants of this approximation is generallythat with the absorption of a photon an electron is virtuallyinstantaneously transferred to a higher energy state and all of thenuclei in the system appear as if they are fixed in place during thisprocess. The consequences of this are, in some cases, that an excitationevent will be the composite of a number of unique structuralconfigurations in an emissive material. As a result, the absorptions ofemissive materials may also have ranges of energy, in some embodiments,that are a result of the different environments and structuralconfigurations that the materials experience. This term, reflected inthe description of the energy range over which the material absorbslight to populate a given excited state, is described as an absorptionband. For example, in solution there may be many configurations ofsolvent molecules around an emissive material. In a solid form there canbe a distribution of different organizations of a matrix that supportsan emissive material. The internal dynamics of the emissive materialsmay also play a role and different thermal vibrations can lead to manydifferent geometries of an emissive material that are instantaneouslyexcited by the absorption of a photon.

Optical absorption bands of a material are generally characterized bythe absorption maxima. This refers to the wavelength (energy) of thepeaks in a plot of photon absorption efficiency as a function ofwavelength. If a material has an absorption maximum close to 450 nm thena very efficient excitation can be expected when illuminated with asmartphone light source. The width of an optical absorption band isoften described by its full width at half maximum (FWHM) and can bereported in nanometers. Without wishing to be bound by theory, as aresult of the fact that the absorption occurs over a range ofwavelengths, it is possible that a material with an absorption maximumthat is of higher energy than 450 nm can be excited by the light sourceof a smartphone (or other consumer electronics). The FWHM of a materialcan in some cases be more than 20 nm, in other cases, more than 40 nm,in others more than 60 nm, in others more than 100 nm. As a result, theabsorption maximum need not be precisely at the same wavelength as thesmartphone light source output, but a component of the absorption mayoverlap with the spectral output of the smartphone's light source. Forexample, a finite intensity of the light source at a region where thereis a finite absorption of the emissive material, is suitable in someembodiments. A material exhibiting an optical absorption that overlapswith the light output of a smartphone is said, in some embodiments, tobe smartphone excitable. Without wishing to be bound by theory, the morephotons absorbed by a material the brighter the emission from theexcited material. In some embodiments, it can be an advantageous tocreate the brightest emission possible using the smartphone's lightsource. However, when the smartphone is used to detect non-steady-stateemissions, signals may be detected even from very weak emissionintensities as a consequence of the methods ability to eliminate ordiscriminate from background optical signals. Different emissivematerials may also have different emission efficiencies for theconversion of the absorbed photons to fluorescence and phosphorescencesignals. The efficiency may depend, for example, on one or both of thematerial and the environment.

Variations in emission efficiencies can be used, in some embodiments, tocreate information about the immediate environment of the emissivematerial or its previous history. The efficiency of the fluorescence andphosphorescence is referred to as the quantum yield. A quantum yield of1.0 implies that 100% of the absorbed photons are converted to photonsemitted as fluorescence and phosphorescence. A quantum yield of 0.1implies that 10% of the absorbed photons are converted to photonsemitted as fluorescence and phosphorescence. There are typically losses,but there are materials that approach quantum yields of 1.0, which isthe theoretical limit for simple processes. As such, it is generallypossible to have materials that can undergo what is generally referredto as singlet fission, wherein an initial excitation produces a singletstate that can separate to give two triplet states. Hence, it istheoretically possible to get multiple photons emitted from a singlephoton absorbed. It is also possible for a photon to trigger a reactionthat can cause the release of multiple photons. In some embodiments,there may be a chemical or electrical potential built up in the materialthat is released with the absorption of a photon. For example, a photontriggered chemiluminescence reaction may, in some embodiments, produce alarge number of emitted photons from a single absorption event.

Beyond the overlap of the emissive material's absorption bands with thesmartphone's light source, other desirable properties that areapplication specific include, but are not limited to, lack of toxicity,low cost, excited state lifetime, chemical stability, interactions withspecific chemical signals, optical anisotropy, efficiency of theconversion, charge transfer character, resistance or susceptibility todegradation via optical excitation, thermal sensitivity orinsensitivity, sensitivity or insensitivity to the nature of itssurroundings, thermal stability or instability, ability to fabricateobjects in a process that can be readily implemented in an existingmanufacturing process, and the inability of a third party to deduce thetrue identity of the emissive material.

In some embodiments, the use of signals acquired under the combinedconditions of steady-state and non-steady-state emission, oralternatively under non-steady-state, are combined with a conventionalsmartphone operated by a program (app). Articles, sensors, and assaysthat can be read and analyzed using commercial smartphones in thismanner will find wide utility (e.g., considering the fact that mostadults and teenagers worldwide currently have personal smartphones). Theinventors of the embodiments described herein have recognized thatselection of appropriate emissive materials that provide informativesignals is advantageous to realizing the potential of smartphones asreaders in the described applications.

For example, there is an abundance of suitable organic dyes capable ofefficient prompt-fluorescence and many of these materials arecommercially available. Prompt-fluorescent dyes are often used toprovide brighter colors in articles. For example, bright fabrics canhave emissive dyes. There are dyes that can even be applied to food, andhence safe to eat, that display prompt-fluorescence in the visiblerange. The use of prompt-fluorescent dyes in commercial products andrelated methods to integrate these materials into articles issufficiently established that one skilled it the art would be able,based upon the teachings of this specification, select other candidatematerials and fabrication methods. Such materials and methods aredescribed in more detail, below.

A number of materials that comprise a delayed-fluorescence by theThermally Activated Delayed Fluorescence (TADF) mechanism may besuitable in accordance with embodiments described herein. TADF materialsare described in more detail, below. In some embodiments, the TADFmaterials may be organic in nature and/or may be systematicallydesigned/modified and fabricated to produce compositions with thedesired absorption and emission properties. Under the conditions ofoptical excitation, TADF materials generally initially displayprompt-fluorescence as a result of the fact that the initial excitedstate is a singlet state. However, without wishing to be bound bytheory, conversion to the triplet state competes with directprompt-fluorescence and produces an additional relaxation channel bydelayed-fluorescence. In some cases, the delayed-fluorescence of theTADF material is the dominate method by which the excited statesradiatively relax to the ground state. In other cases, theprompt-fluorescence is the dominate method by which the molecule emitsphotons. However, in the latter case there may still be a measurable,and hence informative, delayed-fluorescence signal. The dual processesobserved in TADF materials may be important and may provide additionalinformation. In particular it is found that the properties of TADFmolecules may vary based on solvent and the rigidity, polarizability,and dipoles of the host matrix material. Specifically, the fact that theHOMO and LUMO are generally localized to different portions of moleculesundergoing TADF, creates charge transfer character in the excited state.As a result, TADF materials may produce steady-state photon emissionevents as well as non-steady-state photon emission events, in someembodiments.

Prompt-fluorescence materials, and delayed-fluorescence materials,including TADF materials, are described in more detail, below.

In some embodiments, the articles and methods described herein usecapture emission events having different timing. Advantageously, someembodiments demonstrate how the fusion of information producesenhancements in the sensitivity and fidelity of biological diagnostics,including, but not limited to, lateral flow assays (LFAs) and otherassays used to determine, for example if a biomarker is present.Embodiments described herein may be adapted to work with other methods,for example with loop-mediated isothermal amplification (LAMP) fornucleic acid detection and/or vertical flow assays. Different opticalfeatures, which may be in the form of images, portions of images (e.g.,one or more pixels), and any other signals captured by one or morephotosensitive elements, may be captured, in some embodiments, in a waythat provides complementary information. For example, detected photonsassociated with the diagnostic assay may be, in some embodiments,collected within different time domains ranging from those collectedimmediately, with or without external excitation, to those collectedafter a time delay (e.g., ranging from 10 nanoseconds to seconds ormore) e.g., relative to an optical excitation. Advantageously, thecombination of data and/or images taken under these different conditionsprovides for superior methods as compared to some traditional diagnosticassays. Various classes of materials and processes that enable thedifferent timed processes in such embodiments are also described herein.

In some embodiments, the embodiments described herein may advantageouslybe used to monitor compliance of a medical subject (e.g., of a subjecttaking a pharmaceutical agent, of a subject participating in a clinicaltrial). For example, in some embodiments, the article and/or emissivespecies may comprise or be associated with an compound from the FDA's“Generally Recognized as Safe” Substances (GRAS) database and/or listedin 21 C.F.R. § 182, each of which are incorporated by reference hereinin their entirety for all purposes. By way of example only and withoutwishing to be limited as such, in some embodiments the GRAS isriboflavin. Such GRAS molecules may be incorporated e.g., into a capsule(e.g., comprising a pharmaceutical agent) such that the molecule may bedetected in a fluid produced by a subject (e.g., saliva, urine, etc.).

The term “subject,” as used herein, refers to an individual organismsuch as a human or an animal. In some embodiments, the subject is amammal (e.g., a human, a non-human primate, or a non-human mammal), avertebrate, a laboratory animal, a domesticated animal, an agriculturalanimal, or a companion animal. In some embodiments, the subject is ahuman. In some embodiments, the subject is a rodent, a mouse, a rat, ahamster, a rabbit, a dog, a cat, a cow, a goat, a sheep, or a pig.

In an exemplary set of embodiments, an identity or characteristic of achemical and/or biological species (e.g., reaction, presence, etc.) isdetermined by combining a first and second electromagnetic radiationsignal. In some embodiments, the first signal comprises at least a firstphoton emission event. In some embodiments, the second signal comprisesat least a second photon emission event. In some embodiments, the firstphoton emission event and the second photon emission event may occurover different time scales. For example, in some embodiments, the firstphoton emission event may occur during less than or equal to 10nanoseconds of an excitation event that caused the first photon emissionevent. In some embodiments, the second photon emission event may occurat least 10 nanoseconds after the excitation event that caused thesecond photon emission event.

In some embodiments, the steady-state photon emission occurs while anemissive material is being continuously excited by a light source thatstable and/or static (e.g., static relative to the rate at which aphoton emission is collected). In some embodiments, a light source couldbe flickering at a very high frequency, which on average will produce arelatively static excitation over the time period that a photon emissionis collected. In some such embodiments, the emissive material produces arelatively constant intensity emission. In some embodiments, thesteady-state nature of the emission is substantially lost within lessthan or equal to 10 nanoseconds (e.g., less than or equal to 10nanoseconds, less than or equal to 8 nanoseconds, less than or equal to6 nanoseconds, less than or equal to 4 nanoseconds, less than or equalto 2 nanoseconds, less than or equal to 1 nanosecond, less than or equalto 0.5 nanoseconds) after removal of the excitation that caused theemission. In some embodiments, the non-steady state photon emissioncomprises a continued emission of photons from an emissive material,where the continued emission occurs at least 10 nanoseconds (at least 10ns, at least 20 ns, at least 50 ns, at least 100 ns, at least 200 ns, atleast 500 ns, at least 1 μs, at least 10 μs, at least 50 μs, at least100 μs, at least 500 μs, at least 1 ms, at least 5 ms, at least 10 ms,at least 50 ms, at least 100 ms, at least 500 ms, at least 1 s, at least2 s, at least 3 s, at least 4 s, at least 5 s, at least 6 s, at least 7s, at least 8 s, at least 9 s, or at least 10 s) after the excitationthat caused the emission is removed. For example, in some cases, afterremoval of the excitation that caused the emission, the intensity of theemission may change (e.g., decrease, increase) and/or is in anon-steady-state.

Emissions, as described herein, generally refer to photons produced inany way (e.g., including the product of fluorescence, phosphorescence,chemiluminescence, scattering, and/or reflection) where the photonsdefining the emission are measured in the system/process of theinvention. In some embodiments, the first emission event is produced(e.g., in part, in whole) by a species which may be isolated or in amixture, including a minor component in a mixture, where the species hasa less than 10 nanosecond excited state lifetime. For example, in someembodiments, the first photon emission event comprises an emission froman emissive species having an excited state lifetime of less than orequal to 10 nanoseconds, less than or equal to 8 nanoseconds, less thanor equal to 6 nanoseconds, less than or equal to 4 nanoseconds, lessthan or equal to 2 nanoseconds, less than or equal to 1 nanosecond, lessthan or equal to 0.5 nanoseconds. In some embodiments, the first photonemission event comprises an emission from an emissive species having anexcited state lifetime of greater than 0.1 nanoseconds, greater than 0.5nanoseconds, greater than 1 nanosecond, greater than 2 nanoseconds,greater than 4 nanoseconds, greater than 6 nanoseconds, or greater than8 nanoseconds. Combinations of the above-referenced ranges are alsopossible (e.g., less than or equal to 10 nanoseconds and greater than0.1 nanoseconds). Other ranges are also possible.

In some embodiments, the first photon emission event comprises asteady-state emission (e.g., a steady-state photon emission event).Those of ordinary skill in the art would understand, based upon theteachings of the specification, that the first signal may comprisereflection (e.g., reflected electromagnetic radiation, scatteredelectromagnetic radiation) such that the first photon emission event isa result of reflection. Signals comprising reflection are described inmore detail, below.

In some embodiments, the first photon emission event and the secondphoton emission event are caused by the same excitation event. In someembodiments, the first photon emission is caused by a first excitationevent and the second photon emission is caused by a second excitationevent, different than the first excitation event (e.g., different inwavelength, different in intensity, starting and/or occurring atdifferent times, occurring for different lengths of time, oscillating inintensity as a function of time).

In some embodiments, the first photon emission event corresponds to asteady-state emission (e.g., caused by the excitation event).

In some embodiments, at least a portion of the first photon emissionevent occurs substantially instantaneously (e.g., in response to anexcitation event that causes the first photon emission event). In someembodiments, at least a portion of the first photon emission eventoccurs within less than or equal to 10 nanoseconds, less than or equalto 8 nanoseconds, less than or equal to 6 nanoseconds, less than orequal to 4 nanoseconds, less than or equal to 2 nanoseconds, less thanor equal to 1 nanosecond, less than or equal to 0.5 nanoseconds of theexcitation event that causes the first photon emission. In someembodiments, at least a portion of the first photon emission eventoccurs within greater than 0.1 nanoseconds, greater than 0.5nanoseconds, greater than 1 nanosecond, greater than 2 nanoseconds,greater than 4 nanoseconds, greater than 6 nanoseconds, or greater than8 nanoseconds of the excitation event that causes the first photonemission. Combinations of the above-referenced ranges are also possible(e.g., less than or equal to 10 nanoseconds and greater than 0.1nanoseconds). Other ranges are also possible.

In some embodiments, the second photon emission event comprises anemission from an emissive species having an excited state lifetime(e.g., an emissive time period) of at least 10 ns, at least 20 ns, atleast 50 ns, at least 100 ns, at least 200 ns, at least 500 ns, at least1 μs, at least 10 μs, at least 50 μs, at least 100 μs, at least 500 μs,at least 1 ms, at least 5 ms, at least 10 ms, at least 50 ms, at least100 ms, at least 500 ms, at least 1 s, at least 2 s, at least 3 s, atleast 4 s, at least 5 s, at least 6 s, at least 7 s, at least 8 s, atleast 9 s, or at least 10. In some embodiments, the second photonemission event comprises an emission from an emissive species having anexcited state lifetime of 10 s or less, 5 s or less, 2 s or less, 1 s orless, 500 ms or less, 100 ms or less, 50 ms or less, 10 ms or less, 5 msor less, 1 ms or less, 500 μs or less, 100 μs or less, 50 μs or less, 10μs or less, 1 μs or less, 500 ns or less, 200 ns or less, 100 ns orless, 50 ns or less, 10 ns or less, 5 ns or less, or 1 ns or less.Combinations of the above referenced ranges are also possible (e.g., atleast 10 ns and 10 s or less). Other ranges are also possible.

In some embodiments, the second photon emission event comprises anon-steady state emission (e.g., a non-steady-state photon emissionevent).

In some embodiments, the second photon emission event occurs at least 10ns, at least 20 ns, at least 50 ns, at least 100 ns, at least 200 ns, atleast 500 ns, at least 1 μs, at least 10 μs, at least 50 μs, at least100 μs, at least 500 μs, at least 1 ms, at least 5 ms, at least 10 ms,at least 50 ms, at least 100 ms, at least 500 ms, at least 1 s, at least2 s, at least 3 s, at least 4 s, at least 5 s, at least 6 s, at least 7s, at least 8 s, at least 9 s, or at least 10 s after removal of theexcitation event that caused the second photon emission event. In someembodiments, the second photon emission event occurs. 10 s or less, 5 sor less, 2 s or less, 1 s or less, 500 ms or less, 100 ms or less, 50 msor less, 10 ms or less, 5 ms or less, 1 ms or less, 500 μs or less, 100μs or less, 50 μs or less, 10 μs or less, 1 μs or less, 500 ns or less,200 ns or less, 100 ns or less, 50 ns or less, 10 ns or less, 5 ns orless, or 1 ns or less after removal of the excitation event that causedthe second photon emission event. In some embodiments, the second photonemission event occurs. Combinations of the above referenced ranges arealso possible (e.g., at least 10 ns and 10 s or less). Other ranges arealso possible.

In some embodiments, removal of the excitation event refers to adecrease in intensity and/or change in wavelength of the electromagneticradiation source that produces the excitation event. In someembodiments, removal of the excitation event comprises complete removal(e.g., turning off) of the excitation source.

Generally, smartphones provide access to both high-resolution camerasand powerful computational resources for image analysis. To this end,smartphone readers have been developed to improve the accuracy ofcolorimetric assays; however, these approaches leverage temporallystatic data—the image is collected solely from reflected/scatteredlight. For example, and without wishing to be bound by theory,reflected/scattered light is generally time invariant with a staticlight source and is said to be steady-state. With suitable excitationand potentially filters a steady state fluorescence signal may also beobtained, in some embodiments. As described herein, the inventorsdiscovered and recognized that combining e.g., the reflected/scatteredand emitted light in a time-sequenced (steady state and non-steadystate) processes provides access to richer information which may be usedto significantly improve the sensitivity and accuracy of assays. Forexample, fusing steady-state and non-steady-state emission informationin accordance with some embodiments dramatically enhances assay fidelitybeyond what is possible with current smartphone and portable readermethods resulting in improved biological diagnostics.

As described herein, in some embodiments, optical detection of one ormore emissions is performed using a smartphone, optionally incombination with separate excitation sources or a single excitationsource.

In some embodiments, the excitation source(s) are a component of theconsumer electronic device (e.g., integrated with the consumerelectronic device).

Advantageously, such systems described herein provide for more robustassays with increased sensitivity compared to assays that require visualanalysis or utilize simple readers configured to analyze only a singletype of signal. The term “signal” as used herein refers to a measurementof the intensity of light, it impinging on the reader and also aprocessed version (e.g., an image) of such measurements. In someembodiments, the wavelength of the light, its polarization, and/or itsspatial distribution provide key information (e.g., a characteristic oridentity of an emissive species). Embodiments described herein are notgenerally limited to use with a smartphone and any suitable readerincluding electronics and optics that are used to capture and processemissions from an assay in accordance with the techniques describedherein may instead be used. In some embodiments, there are advantages tousing a smartphone (or other consumer electronic device) as it leveragesexisting hardware, contains an array of on-board sensors for datafusion, provides facile location tracking and communications, and thatsmartphones have become ubiquitous.

One of ordinary skill in the art would understand, based upon theteachings of this specification, that a smartphone or related equipmentmay not necessarily capture an image, and/or might not even have theability to create an image. In some embodiments, the presence of asteady-state and non-steady state emission, from one or more species,provides data from at least the non-steady state emission signal, andoptionally from both the steady state (photon) emission signal and thenon-steady state (photon) emission signal (e.g., fusion of signals),which corresponds to desired data (e.g., corresponding to acharacteristic and/or identity of a desired species).

In an exemplary set of embodiments, a smartphone reader modality inlateral flow assays (LFAs) is colorimetric detection. Although thismethod may be used with light sources, the images are generally createdas a result of subtractive color and the smartphone is configured todetect reflected (or scattered) light. In some cases, reflected lightmay comprise a relatively noisy signal. Without wishing to be bound bytheory, such a noisy signal may be due to the presence of reflectedlight from elements beyond the relevant signal for which the diagnosticis based. In some cases, these stray non-specific signals may vary e.g.,as a consequence of the direction of the incident light and dynamicchanges in incident light intensity. Colorimetric signals neverthelesscan provide other useful information including images of the assaycartridge, markers that may be used for alignment, text, numbers,pictures, logos, bar codes, or QR codes. Images, in some embodiments,are the result of subtractive color, wherein part of the electromagneticspectrum is absorbed. Colorimetric analysis may be used, in some cases,with materials that are substantially reflective and/or produce color byreflection of particular wavelengths. In the case of colorimetricreflected light, there is generally no detectable delay between thelight interacting with the dye, nanoparticles, or reflectors in theassay and the arrival of the light at the reader (smartphone). Anexemplary suitable alternative to pure colorimetric readers are thosethat make use of luminescent signals. For example, to create anluminescent state, a photon may be absorbed by the material to create anexcited state that has a finite lifetime. There are different types ofluminescent materials and excited state lifetimes that are used tocreate signals.

Some embodiments described herein generally are related to methods offusing different types of signals and the time sequences thereof tocreate methods to read biological assays in ways that provide forsuperior sensitivity and accuracy to existing methods. According to someembodiments, a component of a system (e.g., an image sensor, aphotosensitive component) detects at least a portion of a detectableemission produced by an emissive species over the time period whereinthe emitting species is being illuminated (excited). In some cases, thecomponent detects light after the illumination is removed over anemission time period the length of which is related to the emissionlifetimes of the emissive species in the composition. A person ofordinary skill in the art would understand that an emissive species mayproduce a detectable emission through, for example, phosphorescence orfluorescence. An emissive species may also be detected byreflected/scattered light in the case that it has an absorption in theregions of the electromagnetic spectrum that are being excited. It isthe case that many emissive species have color and hence may be detectedin this way. A person of ordinary skill in the art would also understandthat an emission time period or emission lifetime characterizes the rateat which an emissive species emits electromagnetic radiation after anyexcitation radiation has been removed (e.g., after a pulse ofelectromagnetic radiation has been emitted by an excitation component).

In some embodiments, prompt-fluorescent signals are generated byemissive materials that have excited state lifetimes less than or equalto 10 nanoseconds (e.g., less than or equal to 10 ns, less than or equalto 5 ns, less than or equal to 2 ns, less than or equal to 1 ns).Prompt-fluorescent materials represent the most common type of emissivematerials, and dye molecules displaying prompt-fluorescence are widelyavailable. Although the excited state of these materials has ameasurable lifetime, the times are sufficiently short such thatresolution of signals based on lifetime is not readily performed withthe inexpensive hardware of a smartphone. To collect prompt-fluorescencewith a smartphone the materials would generally be simultaneouslyexcited by a light source, while the image is collected by standardoptical detectors (for example CMOS imaging chips) commonly found indigital cameras or smartphones. When the excitation is removed thematerials, in some embodiments, will relax within a few nanoseconds andthe post illumination signal will go away before a time gated detectionwith these devices can capture substantial amounts of emitted light. Asa result, to accurately record a prompt-fluorescence signal with asmartphone of digital camera, the excitation may be sustained during theduration of the measurement. This effect generally yields a constant(steady-state) emission, provided the excitation source is stable andthe emissive molecule doesn't optically/chemically degrade (irreversiblybleach out) over the timescale of the measurement.

In the context of this invention the measurement of an emissive signalcoming from a source with a lifetime that is less than or equal 10nanoseconds in duration is detected while simultaneously exciting theemissive material and is said to be a steady-state measurement.

An exemplary fluorescent material that displays an excited statelifetime longer than 10 nanoseconds and up to 50 microseconds in thecontext of this invention is said to be a delayed-fluorescence signal.Similar to prompt-fluorescence, the major component of the emissiongenerally comes from the relaxation of a singlet (electron spin paired)excited state and generally doesn't require a spin interconversionduring the emission process. Organic materials, which generally lackheavy atoms from the third row or lower in the periodic table, arecapable of delayed-fluorescence provided there is a mechanism for thedelay. The delay mechanisms may be, in some cases, the result ofequilibrium processes that occur in an excited material. One mechanismis known as thermally activated delayed-fluorescence (TADF). TADFmaterials are described in more detail, below. In this process, withoutwishing to be bound by theory, a material will have singlet (spinsaligned antiparallel) and triplet (spins aligned parallel) excitedelectronic states that are sufficiently close in energy that they are inthermal equilibrium under ambient conditions. In the vast majority ofmaterials, the triplet state may be lower in energy and hence for amajority of the time the material's excited state resides in the tripletstate. In materials that lack heavy atoms, there is generallyinsufficient spin-orbit coupling to facilitate efficient direct emissionfrom the triplet state, and hence the triplet state is a long lived lowemissive (dark) state. However, and without wishing to be bound bytheory, in TADF materials there is generally an equilibrium wherein theexcited state can convert back to the singlet and then rapidly relax tothe ground state by emitting a photon. The time spent in the tripletproduces a delay and hence a delayed-fluorescence with excited statelifetimes larger than 10 nanoseconds up to 50 microseconds. Othermethods to create delayed-fluorescence are also possible including, forexample, processes wherein charge separated states are generated byelectron transfer or alternatively conformational changes such as atwisted charge separated excited state. In some embodiments, therecombination of the charges can create a singlet state after a delaythat yields delayed-fluorescence. The upper limit on the time scale ofdelayed-fluorescence is not a firm number, but in practice there areoften competing non-emissive thermal relaxation processes. Theseprocesses depopulate the excited state under ambient conditions andthereby result in relatively very weak signals being produced at longertimescales because only a small fraction of the excited state willsurvive for that length of time with competing relaxation processes. Thecompeting relaxation methods may be attenuated by lowering thetemperature or placing the emissive species in a rigid matrix.

Delayed-fluorescence as described herein may, in some embodiments, beread (detected) by a smartphone, digital camera, or equivalent imagecapture device providing the detector used for image capture can collectdata over the time period with sufficient emission intensity to allowdetection. For example, in this process the optical input (excitation)used to create excited states with lifetimes greater than 10 nanosecondsis time synchronized with the image capture hardware using pulsed lightflashes, rapid flashing, or frequency modulation of the excitationsource. It is important to note that the time synchronization betweenthe image capture and the excitation in the context of this invention isnot necessarily absolute, but may be relative. In other words, in somecases, there may be no need for a precise absolute timing of pulses orthe phase of the frequency of a modulated excitation and the rate ofimage capture of the image capture device. For example, the frequency ofa pulsed or modulated light source need not be commensurate with theimage capture device. The signals may be affected, in some cases, byboth the time periods of the image capture and the excitation. In someembodiments, relative times and/or frequencies may be deducedcomputationally Advantageously, such a feature negates the need forprecision in the absolute timing of these events. Complex excitationprofiles may be applied that involve mixtures of these processes. In thecontext of this invention, time synchronization of the input excitinglight generally refers to light intensity that varies as a function oftime. In some embodiments, the detection system is capable of andconfigured to detect(ing) these non-steady state process to extractinformation pertaining to the time domain. These methods may allow, insome cases, for time phased (delayed) capture of the emitted light suchthat the delayed emission may be selectively detected and backgroundsignals may be eliminated. In some embodiments, the emitted light isdetected after the excitation light is turned off and when shielded fromambient (stray light) the delayed signal is captured on a substantiallyor completely dark background. Alternatively, the time variance of theexciting light may be used to select signals coming from the emissivestate of interest in a complex background containing stray and scatteredlight.

A number of suitable materials have highly emissive excited tripletstates, which in the context of this invention displayprompt-phosphorescence with excited state lifetimes of 10 nanoseconds to50 microseconds (e.g., 10 ns to 20 ns, 10 ns to 50 ns, 10 ns to 100 ns,10 ns to 500 ns, 10 ns to 1 μs, 10 ns to 5 μs, 10 ns to 10 μs, 10 ns to50 μs, 10 ns to 100 μs, 10 ns to 500 μs, 10 ns to 1 ms, 10 ns to 5 ms,10 ns to 10 ms, 10 ns to 50 ms, 10 ns to 100 ms, 10 ns to 500 ms, 10 nsto 1 s, 10 ns to 5 s, 10 ns to 10 s, 50 ns to 100 ns, 50 ns to 500 ns,50 ns to 1 μs, 50 ns to 5 μs, 50 ns to 10 μs, 50 ns to 50 μs). In thiscontext, the materials contain heavy atoms that interact with theexcited state. The heavy atom effect as described herein generallyrefers to the ability of these elements to provide spin-orbit couplingsufficient to allow an excited state to undergo a facile spininterconversion during the emission process. In this method a tripletexcited state relaxes directly to a singlet ground state with theemission of a photon. The initial excited state that is populated bylight absorption will generally be a singlet in nature, because, withoutwishing to be bound by theory, singlet to singlet electronic transitionsare much more efficient in the absorption of light. Once the firstexcited singlet state of a material is created, the heavy atom effectwill, in some embodiments, produce fast intersystem crossing and createa lower energy triplet state. Without wishing to be bound by theory, fortriplet states to directly emit light, one of the electron spins mayflip during the emissive relaxation to the singlet ground state and thespin-orbit coupling provided by the heavy atoms can make this processhighly efficient. Heavy atoms are generally defined as elements thathave a nuclear core structure larger than neon. For example,phosphorous, sulfur and chlorine may all, in some contexts, produce somelevel of a heavy atom effect. However, heavier elements with nuclearcores bigger than argon may generally yield larger heavy atom effects.The heavy atom effect may also be enhanced, in some cases, by attachingadditional heavy atoms to a molecule. For example, the attachment ofhalogens such as Cl, Br, or I to aromatic molecules with the addition ofmore halogens enhancing spin interconversion processes, may result inthis effect. A number of transition metal containing materials displayprompt-phosphorescence and there are many examples of materials thatcontain metal-carbon bonds (organometallics) as well as materials thatcontain metal-nitrogen, metal-sulfur, metal-phosphorous, or metal-oxygenbonds (metallo-organics) that connect them with electronicallydelocalized organic molecular subunits and are suitable for use with theembodiments described herein. The heavy atoms also need not becovalently bound to the materials and physical contact between theelectron clouds of the heavy atoms and emitting materials may also giveprompt-phosphorescence. Similar to delayed-fluorescence the emissivesignals may be read by a smartphone, digital camera, or equivalent imagecapture device when paired with a time sequenomptced excitation.

Another class of molecules relevant to this disclosure are thosedisplaying prompt-phosphorescence. In order to have sufficient radiativerates for the conversion of the triplet excited state to the singletground state, which generally requires a spin interconversion process,most materials need a spin orbit coupling component that is afforded byelectronic coupling with heavy elements. It is possible to obtainefficient prompt-phosphorescence in organic compounds bearing heavyatoms. One such exemplary material is Erythrosin B shown below, whichhas four iodine atoms attached to the chromophore that promotesphosphorescence. Advantageously, this material is particularlyattractive as it is used as a food dye and is considered non-toxic.However, embodiments described herein are not intended to be limited assuch and other materials are also possible. Erythrosin B generallydisplays two different forms and in its deprotonated anionic state isemissive and excitable by the light sources associated with smartphones.Upon protonation to its neutral state, the most favored isomer is onethat lacks extended conjugation and is non-emissive. There are otherrelated halogenated dyes, such as the bromide derivative of Erythrosin Bknown as Eosin, that display similar behavior. Additionally, Rose Bengal(4,5,6,7-tetrachloro-2′,4′,5′,7′-tetraiodofluorescein) has a closelyrelated structure with the addition of four chlorine atoms to thependant phenyl. The acid-base reactivity of these systems can be used toswitch between emissive smartphone excitable and non-emissive materialsthat cannot be excited by a smartphone. This property may be used, forexample, in applications for the detection of molecular signatures,thermal history, ionizing radiation, physical alteration, mechanicalstress, fractures, oxygen, moisture, and/or UV radiation.

Although the heavy iodine atoms are covalently bound to chromophores inErythrosin B, non-covalent interactions may also give significantphosphorescence. For example, physical mixtures of an organo-iodidematerial and another chromophore of interest that may be excited by thelight source of a smartphone can display phosphorescence, in someembodiments. These interactions can occur through van der Waals typeinteractions or stronger interactions (e.g., using what is generallyreferred to as halogen bonding). In this latter scheme, without wishingto be bound by theory, a halide (typically iodine) generally behaves asa Lewis acid and forms a weak complex with the Lewis basic groups of theselected chromophore. Non-covalent associations may be promoted insolids and thin films and thereby produce higher phosphorescenceintensities, which again can be modulated by interaction with theirsurroundings or different stimuli.

The incorporation of halides, such as bromine and iodine, into organicchromophores may be an advantageous approach to create different organicphosphors, in some embodiments. When the lifetimes are very long, it maybe advantageous for the materials to be located in a rigid matrix, e.g.,which can optionally be microcrystals of the emissive material in somecases. Alternatively, such materials may be embedded in other molecularpolymeric or inorganic hosts. Examples of halogen containing phosphorsthat can be excited by the light sources of a smartphone are shownbelow. It should be noted that the sulfur groups may also produce heavyatom effects and thereby promote phosphorescence.

Carbon dots are another class of emissive materials which may besuitable for use with the embodiments described herein. These materialsare complex and their chemical structures are non-uniform and as aconsequence are not precisely known. They are, in some cases, producedby different types of thermolysis and often contain nitrogen and oxygenheteroatoms. The compositions thereof may be determined by the startingmaterials and the thermolysis or combustion method. Carbon nanodots maybe produced, for example, by laser-ablation of carbon materials,electrolysis of carbon materials, heating organic materials at hightemperature, pyrolysis of nanocomposites or organic materials with othermaterials including silicates, hydrothermal/solvothermal treatments oforganic materials, and microwave heating of organic materials. The factthat carbon dots are often created under high temperature may, in somecases, generally impart high thermal stability to these materials. Assuch, carbon dots are often suitable for relatively high temperaturemanufacturing processes or in materials, such as engine oil, that willencounter high temperatures. In some cases, such materials display whatis generally considered to be singlet emission (fluorescence) withexcited state lifetimes longer than 10 nanoseconds. These longer singletemissions are generally referred to as delayed-fluorescence. It ispossible that different symmetry electronic states within the materialsproduce sufficient spin-orbit coupling to allow forprompt-phosphorescence. In other cases, the lifetimes may exceed thosetypically associated with prompt-phosphorescence. In these systems, thespin orbit coupling is generally not strong and the radiative relaxationof the triplet states is slow. However, without wishing to be bound bytheory, as a result of their rigid character, other non-radiativeprocesses are attenuated such that significant emission is observed inthe delayed-phosphorescence time regime. Alternatively, such materialsmay undergo TADF type processes as a result of thermal equilibriumbetween closely spaced singlet and triplet states. The energy levels incarbon dots generally have considerable dispersion and some variants canbe effectively excited by the light sources of smartphones to createsteady-state photon emission events as well as non-steady-state photonemission events.

A general class of prompt-phosphorescent materials include, for example,organometallic compounds that have what are known as ortho-metallatedring structures. Such materials generally comprise cyclic ringstructures that involve an organic ligand and have at least onecarbon-metal bond. Such a combination may, in some cases, give rise tofavorable electronic states and a strong heavy atom effect from thetransition metal. There are a number of materials that can be readilyexcitable by the light sources of smartphones. Non-limiting examplesbased on Os, Ir, and Pt are described herein. Such compounds can beoptionally substituted to produce the desired properties andcompatibilities. Similar ligands may be used to create otherprompt-phosphorescent compounds with these metals and others. In somecases, the ortho-metalated compounds are selected to be stable underambient conditions. For example, heavier transition metal elements andpost transition metal elements such as Pb and Bi may provide stablecarbon-metal bonds.

There are also other classes of organometallic emitters that can bedesigned to have absorbances capable of being excited by the lightsources of smartphones. Carbon compounds wherein the C-M bonds arestrong are non-limiting examples. For example, stable Au and Ptcompounds containing “M-CC-Ar” linkages are generally very stable andmany are emissive. By selecting appropriate alkynes and Ar groups,different materials may be produced that are excitable by the lightsources of smartphones.

Metallo-organic compounds, wherein metals are bound to organic ligandsthrough non-carbon-based groups, may also display efficientprompt-phosphorescence. Non-limiting suitable examples are based on Ruand Os and the compounds described below are non-limiting examples ofprompt-phosphorescent compounds that may be excited by smartphone lightsources to create non-steady-state photon emissions. There are manyother potential variations of compounds containing nitrogen boundligands to transition metals that display prompt-phosphorescence and areexcitable by the light sources of smartphones (or other consumerelectronic devices). The charged nature of the compounds shown allow, insome embodiments, for electrostatic assembly processes and/or the use offunctional counterions that can enable specific applications.

Metallo-porphyrins are another suitable class of metallo-organicmaterials that display prompt phosphorescence and can be excited by thelight source of a smartphone to create non-steady-state photon emissionevents. Porphyrins have a rich coordination chemistry and may becomplexed by many different transition metals. The porphyrins can bedesigned to be anionic and these compounds can create electrostaticassemblies. Pd and Pt porphyrins, for example, display highsensitivities to oxygen quenching, thereby enabling emissive sensors tobe produced.

Other porphyrins are also possible and may be excited with the lightsource of a smartphone (or other consumer electronic device). The basestructure may be substituted with a wide variety of functionalities atall of the ring carbon centers. For example, the pyrrole rings may behalogenated and oxygenated, in some embodiments. Oxygenation may giverise to systems having ketones such as the non-limiting examples shownbelow, which can display prompt-phosphorescence and are generallycapable of creating non-steady-state photon emission events. Although Ptand Pd porphyrin compounds are described herein, a number of othermetals and in some cases even the metal free porphyrins and theirderivatives may be used as smartphone excitable emissive elements. Likeall of the other chromophores, these materials may be used, in someembodiments, to produce steady-state photon emission events.

Other suitable classes of prompt-phosphorescent metallo-organiccompounds and the metals may be bound to the organic ligands by groupsother than nitrogen. For example, they may be bound through oxygen,phosphine, or sulfur, in some cases. Those skilled in the art wouldunderstand, based upon the teachings of this specification, that anumber of potential binding modalities between the metals and organicligands may be used to produce electronic transitions with sufficientcoupling to enable effective phosphorescence. It is also possible forcarbophilic metals, in some embodiments, to bind directly to thepi-systems of organic chromophores and facilitate phosphorescence. Forexample, silver ions may be useful as carbophilic cations and to createphosphorescent compositions.

Another suitable type of emissive material suitable for use withembodiments described herein display what is generally referred to inthe context of this invention as delayed-phosphorescence, which isdefined as an emissive material having an excited state lifetime of morethan 50 microseconds (e.g., at least 50 μs, at least 100 μs, at least500 μs, at least 1 ms, at least 5 ms, at least 10 ms, at least 50 ms, atleast 100 ms, at least 500 ms, at least 1 s, at least 2 s, at least 3 s,at least 4 s, at least 5 s, at least 6 s, at least 7 s, at least 8 s, atleast 9 s, or at least 10 s). In this case, and for all of the emissivematerials discussed in the context of this invention, the ranges ofexcited state lifetimes stated are not exclusive. For example, therewill be materials that span the excited state lifetimes defined forprompt-phosphorescence and delayed-phosphorescence. To achieve such longlifetimes the excited states of delayed-phosphorescent materials mustnot have other processes that cause rapid non-radiative relaxation. Formany emissive materials the rate of non-radiative processes will depletethe excited states prior to emitting a significant fraction of thephotons. As such, in some delayed-phosphorescent materials the emissivesites are embedded in very rigid environments such as solid-stateinorganic matrices, with a number of inorganic phosphors displayingdelayed phosphorescence. Other constructions that displaydelayed-phosphorescence include emissive sites based on heavy elementsthat have f-orbitals as their frontier orbitals, such as elements fromthe lanthanide and actinide series. In these materials the electronclouds (defined by their orbitals) involved in the emission arecontracted and the electrons are held sufficiently close to the nucleithat they do not interact strongly with the electrons of thecoordinating ligands. This feature tends to insulate the excited statesfrom the surrounding dynamics and vibrations that contribute tonon-radiative relaxation of the excited states. However, these materialsare not completely immune from their environment and care must be takento design emissive species that produce bright emissions in the contextof a biological diagnostic test. For example, in many cases thecoordination of water (H₂O) to the metal ions can give rise to rapidrelaxation. In some embodiments, substitution of H₂O in thesecompositions for D₂O (heavy water) results in a reduction in thenon-radiative rates and an increase in the intensity of the delayedphosphorescence. Typical elements displaying delayed phosphorescenceinclude but are not limited to europium, terbium, gadolinium, anderbium. Similar to delayed-fluorescence and prompt-phosphorescence,delayed-phosphorescence may be selectively detected by a smartphone,digital camera, or equivalent image capture device when paired with timesynchronized excitation of the material to create an emissive state.

In some embodiments, a light signal that may be of use in these methodsis that of chemiluminescence. In this process a chemical reaction isgenerally triggered either by the addition of reagents or the in situactivation of a reaction pathway to give an excited state. In this case,the timing is caused by a trigger that releases a reagent or activates apathway for chemiluminescence. The trigger may be part of the biologicalassay or performed at the end of the assay. The trigger could beperformed physically, photochemically, or by an electrical impulse.There is, in some embodiments, no need for an optical excitation in thiscase and the signal generated after the trigger of the chemiluminescencewill be collected in steady-state mode by the smartphone, digitalcamera, or equivalent image capture device.

The different optical signals described above and herein may be used ina number of combinations to enhance the sensitivity and fidelity ofbiological diagnostic assays including lateral flow, vertical flow andLAMP assays. Advantageously, the methods and signals described hereinserve to minimize the effects of small movements (jitter) and/or reduceoptical noise e.g., caused by non-specific signals and stray light. Theability to combine images may, in some embodiments, need precision inthe alignment of the images that may be provided by optical (fiducial)markers, reference signals, image analysis, information about the assay,and computational methods. The combination of images collected fromdifferent optical elements collected under alternative illumination orcollected over various time domains is used to determine and mitigateoptical noise.

In some embodiments, color-based (colorimetric) signals are created byeither subtractive color or selective reflection of light and may becollected under ambient conditions or with additional illumination. Thissteady-state signal is time invariant, without wishing to be bound bytheory, if, for example, the incident light remains constant. In someembodiments, time sequencing between the incident light and detectedsignal is not used. In some cases, color changes will accompany thebiological diagnostic as a result of a reaction or the localization of acolored material during the assay. The colorimetric signal may be usedin conjunction with luminescent signals that are all collected e.g., bythe smartphone, digital camera, or other image capture device orcomponent. The images may alternatively, in some embodiments, encodeinformation about the assay including instructions as to the nature ofthe assay, the method that should be used to optimally read the assay,and/or the physical location on the device where the signals of interestare expected. For example, the image may comprise fiducial markers.Images may also be collected, in some embodiments, that provide criticalinformation for calibration and can for example include intensity and/orlifetime data from reference signals that are invariant in the assay.The relative intensities or lifetimes of the assay signals relative tothese reference signals may be used, in some embodiments, to account forother differences that can limit the accuracy of the assay. For example,it could be that the light source used in one assay is brighter thanthat of another. An internal reference may be used, in some cases, toaccount for such variance and provide greater precision and quantitationof the signal. The references may be read separately, before or aftermeasuring the measurement of the signal associated with detecting thesignal of interest, or alternatively could be collected simultaneouslyfrom the same image. In some such embodiments, the reference signal isseparated from the signal associated with the detection event, by havinga different emission wavelength, different location in the image(assay), and/or different excited state lifetime.

Collecting and combining information from multiple images and spatial,wavelength, and time domains advantageously allows for a greater abilityto discern signals from background noise and quantitate signals, in someembodiments. For example, biological diagnostic assays may be conductedin environments that have stray light. In some such cases, the abilityof these methods to differentiate signals from background willadvantageously allow for computational methods to be applied thatincrease the assay's sensitivity and fidelity. In some cases, thecolorimetric signal is collected in response to (external) illumination.In some embodiments, such illumination may be produced by the flash ofthe same smartphone that is reading the assay. In other cases, theillumination is provided by an additional light source. In some cases,the direction of the light source may be used to provide a signal thatminimizes or takes advantage of reflections/scattering or differences inthe optical properties of the assay to enhance the signal. In somecases, the signals read may vary with the polarization of the incidentand/or detected light. In some embodiments, information from the colorand its chromaticity may be collected, which may be measured indifferent ways including, for example, the position on a diagram, therelative intensity of the different color pixels collected with asmartphone, or the intensity as a function of wavelength.

A colorimetric signal may be used, in some embodiments, in conjunctionwith one or more different luminescent signals. For example, whencombined with prompt-fluorescence, both signals may be acquired in asteady-state mode. In some embodiments, the colorimetric signal may becollected under white light illumination and the prompt-fluorescence maybe differentiated by collecting this signal under a different opticalstimulation wherein the luminescent material is excited. This type ofprocess may be used to provide complimentary information. For example,it is possible, in some cases, to selectively excite theprompt-fluorescent material by applying a light source of a particularwavelength.

In some embodiments (e.g., to create a high contrast fluorescencesignal), the light used to excite the prompt-fluorescent material isselected such that it is not detected by the smartphone, digital camera,or other detector. In some cases, there may be a detection advantage ifthe fluorescent signal is detected on a dark background. For example,the excitation may be performed, in some cases, using light that may beexcluded from the detection device by added filters, an absorptivesupport, or by the intrinsic absorption of the optical elements (lenses)in the detection system. One exemplary way to accomplish this featureis, in some embodiments, to use higher energy ultraviolet (UV) light toexcite the fluorescent materials. In some cases, a diagnostic assay maybe read using a colorimetric signal under either ambient light or underwhite light illumination and then combined with the prompt-fluorescencesignal. Advantageously, the colorimetric signal need not be the directresult of a biomolecular detection event but could (in addition oralternatively) provide information about the location wherein thefluorescent signals are expected and/or provide fiducial markers thatmay be used to identify the areas that are to be analyzed. Such image(s)may be collected with or without the aid of illumination and/or in rapidsuccession the prompt-fluorescent material is excited and the signal iscollected. The combined signals may be used, in some embodiments, toensure accurate registration of all signals (mitigate any jitter andprovide calibration) as well as compensate for other optical noise,thereby creating an improved signal. In some cases, the measurement willbe made using a box or other device to prevent stray light from thesurroundings from impinging on the assay. In some cases, both thecolorimetric and fluorescent images will be collected underillumination, with the former using white light and the latter usinglight that will excite the prompt-fluorescent materials, but is filteredfrom the detection device, comprising a smartphone, digital camera, orother optical detection system. The prompt-fluorescence signals may alsobe produced, in some cases, by excitation with a white light source andoptical filters positioned before the detector may be used to reject thewhite light background. The prompt-fluorescence signals also need not bedirectly related to a biological event but could also be used to providefiducial spatial or calibration information. Colorimetric signals may beused, in some embodiments, in conjunction with chemiluminescent signals.The chemiluminescent signal may not require illumination in suchembodiments, and advantageously may be detected in a background thatexcludes stray light.

Colorimetric, prompt-fluorescence, or chemiluminescence signals may alsobe used in conjunction with delayed-fluorescence,prompt-phosphorescence, or delayed-phosphorescence, in some embodiments.For example, the delayed-fluorescence, prompt-phosphorescence, ordelayed-phosphorescence signals may be selectively detected using timesynchronized light excitation in conjunction with the smartphone camera,digital camera, or other detection system. In some cases, the detectionof light in these devices makes use of a shutter mechanism that allowsfor time gated detection of light, as described in more detail, below.Depending upon the lifetime of the emissive species, parameters on thesmartphone or equivalent device may be chosen such that a single imagemay contain information about the lifetime of the emissive species. Inthis way, for example, the signal may evolve throughout the imagecapture. With delayed-phosphorescence a smartphone or digital camerathat can capture entire images may also be used with a simple delaybetween the excitation and the image collection. In some cases, theimages may be captured by using a video (frame) capture option that iscommon to these devices. These images, in some embodiments, are combinedwith other imagery to provide information on the assay, fiducial spatialinformation, calibration, or complementary signals to produce a robustassay.

In many instances in which images are obtained (one example is taking aphoto with a cellphone), a single image is not simply obtained at onemoment in time, but portions of the single image are taken at differenttimes (although over a very short time span) to construct the singleimage. For example, one portion of the image (for example, the topportion) is obtained at a very slightly different time than anotherportion of the image (for example, the bottom portion). With a cellphonecamera, a “shutter” (e.g., an electronic shutter) may block portions ofthe image from forming at different times depending on location in theimage, so that the entire image is not over-exposed, and at anyparticular time, some portion but not the entire image is beingrecorded, but over time (very short) the entire image is constructed.With knowledge of when specific portions of the image were obtained, onecan identify information about what happened with a subject of thatimage at those two (or more) different times and/or over the entire timeperiod of image formation (or a portion of that time period). Forexample, if a feature of an emissive species (chemical or biologicalspecies, emissive tag, or the like) changes on the timescale of imageformation, then the single image formed may be used to determinesomething about that change(s). In some embodiments, an entire image (orimages) comprise a considerable amount of data that is not relevant tothe signals of interest and that analysis may depend on a select numberof pixels. In some such embodiments, a select feature or number ofpixels may constitute the image and/or information from the measurement.In some embodiments, pixels are combined to produce data that representsthe spatial distribution of a signal. For example, an image may reveal avertical line of signal with regards to a horizontal direction. In thiscase, the vertical and horizontal are relative directions and notgenerally absolute. In some embodiments, analysis of the signal maycomprise a sum of the intensity of the pixels along the verticaldirection. In some embodiments, a plot of these summed intensities inthe horizontal dimension provides a method to analyze the totalintensity of the line relative to the background. Such an analysis inconcert with calibration signals may be used, in some cases, to producequantitative measurements in assays.

As will be apparent from the description throughout this disclosure, theinvention(s) includes many variations of the above description, notlimited to any particular type of image, number of images, type ofequipment used to obtain an image, etc.

In some embodiments, an article (such as a diagnostic assay) isassociated with an emissive material comprising an emissive species. Insome cases, the emissive species has an emission lifetime as describedabove and herein. A person of ordinary skill in the art would understandthat suitable emission timelines may be selected, for example, based onthe time resolution of the image sensor. For some image sensors, asuitable lifetime may be on the order of milliseconds, while for otherimage sensors, a suitable lifetime may be on the order of microseconds.Image sensors with faster time responses will generally allow forlifetime-based images to be obtained using emissive species with shorterlifetimes. In some cases, a characteristic of an emissive species (e.g.,identity, authenticity, age, quality, purity, presence) may bedetermined by obtaining an image (or series of images) comprisingtime-dependent information related to an emissive species. In certaininstances, for example, the emission lifetime of an emissive species maybe determined from an image (or series of images). Since the emissionlifetime of an emissive species may be modified by a number of factors,including but not limited to binding or proximity to other molecules(e.g., water, oxygen, carbon dioxide, carbon monoxide), temperature, pH,and radiation exposure, the measured length of the emission lifetime(e.g., the observed emission lifetime, the emission time period) mayprovide information regarding a characteristic of an associated article.In some instances, an emissive material comprising one or more emissivespecies may be used to identify and/or authenticate an associatedarticle.

According to some embodiments, an article (e.g., diagnostic assay) isassociated with an emissive material comprising an emissive species. Insome embodiments, the emissive species is a chemical and/or biologicalspecies. In some instances, an excitation component emitsnon-steady-state pulsed and/or modulated electromagnetic radiation, atleast a portion of which is absorbed by the emissive species. In somecases, a pulsed and/or modulated excitation component can havepolarization, or one or more bands of wavelengths. In some cases,multiple excitation components may be used in sequence and/or may beoverlapping in the time they are applied to an article. In certaincases, the absorbed electromagnetic radiation excites one or moreelectrons of the emissive species to a higher energy state. The one ormore excited states are generally metastable and may, in some cases,relax to a lower energy state (e.g., the ground state) through emissionof electromagnetic radiation, thermal dissipation (e.g., throughvibrational energy transfer), and/or a chemical reaction. The one ormore excited states may, in some cases, also transfer energy toneighboring species, which can be emissive species with differentemission wavelengths, polarizations, and/or lifetimes. When an excitedstate relaxes by emitting electromagnetic radiation, it may produce adetectable emission over a period of time (also referred to as an“emission time period” or “emission lifetime”). In some cases, an imagesensor may detect at least a portion of the detectable emission. Incertain cases, an electronic hardware component (e.g., circuitry, one ormore processors) may subsequently generate an image (or series ofimages) comprising a first portion corresponding to a first portion ofthe emission time period and a second portion corresponding to a secondportion of the emission time period.

In certain cases, an electronic hardware component can generate an imageby capturing electromagnetic radiation (e.g., visible light or otherlight) from different portions of emissions at a number of differentlifetimes. The sequence and time periods over which the image iscaptured may be variable and may be controlled by programing ormodification of the electronic hardware. In this manner, an image (orseries of images) may be used to obtain time-dependent informationregarding the emissive species and/or a characteristic of the article.By collecting different parts of an image at different time periods inrelation to the excitation component, unique images may be produced.These images may be used to convey information about the article andserve as an authentication code. As one non-limiting example, an image(or series of images) may be used to determine the emission lifetime ofthe emissive species. In some cases, the emission lifetime of anemissive species may be modified by binding and/or proximity to othermolecules (e.g., water, oxygen, carbon dioxide, carbon monoxide),temperature, physical alteration, pH, radiation exposure, and/or otherenvironmental factors. In some instances, therefore, the particularemission lifetime value may provide information about a characteristicof the associated article (e.g., the presence or absence of a label, acharacteristic of the environment, information about prior chemical,physical, or other exposures). As another non-limiting example, adifference between a property of the first portion of an image and aproperty of the second portion of the image may provide informationabout a characteristic of the article (e.g., the presence or absence ofa label, a characteristic of the environment, information about priorchemical, physical, or other exposures).

In some embodiments, the emissive species is selected such that theemissive species is present (or produces an emission) if a targetanalyte, is present.

In some embodiments, a shutter mechanism is used that can provide timeresolution using what is known as the rolling shutter, which is used inmany smartphones and digital cameras. The rolling shutter is generallyan electronic mechanism and is related to the electronic reading of theimaging chip. Similar to a classical shutter used in older cameras, therate over which the chips are read may be varied. In smartphones ordigital cameras, a chip detects the light projected onto it bysequentially by reading rows or columns of the photo-detection elementsin rapid succession. The time delay with this reading allows for thedevice to behave in a way that can extract information as a function ofthe lifetime of the emissive species. This information may be extractedfrom a single image by reading the different rows or columns or could beextracted from the overlay of many images collected with different typesof excitation and rolling shutter reading conditions. For example, it ispossible that an excitation wherein the intensity changes with time maybe used in conjunction with a rolling shutter to acquire lifetime data.In this case, the rates at which the excitations are modulated may varyover a large range and will ideally approach similar cycle periods intime to the excited state lifetimes of the different emissive species.By varying the rates of image collection (rolling shutter) rates and theexcitation conditions, it is possible, in some embodiments, toselectively detect different emissive species and minimize backgroundsignals. It is also noteworthy that this method allows for the selectivedetection of multiple different species having different excited statelifetimes within a biological assay. This feature may be combined withthe chromaticity (wavelengths) of the emissive species as well asmethods that use polarization of light to decrease optical noise. Insome embodiments the reader is a conventional smartphone that uses arolling shutter. A critical aspect of the smartphone is the timingbetween the excitation and the speed of the rolling shutter. Anexcitation may be pulsed and entire images collected after a singlepulse. Alternatively, the excitation may be pulsed multiple times duringthe collection of a single image. Additionally, the excitation may becontinuously modulated at one or more varying frequencies throughout thecollection of the images using the rolling shutter mechanism. It is alsopossible that a series of images may be determined that havecombinations of different excitation frequencies and rolling shutterspeeds. In some cases, a reader will initially collect data under manydifferent excitation conditions and rolling shutter conditions.Computational methods may be used to determine which combination ofthese trial excitation and rolling shutter conditions produces thesuperior signal. This signal may be extracted or the reader can makeadditional measurements under the optimal conditions. By way of exampleto illustrate this concept, if a single analysis (or trial measurement)takes 10 milliseconds, it is possible to make 100 separate measurementsin a second. In these ways the smartphone, digital camera, or detectiondevice (reader) may advantageously be used to selectively detect signalswith particular lifetimes in a complex background. For example, undersome conditions the devices may be used to detectdelayed-phosphorescence to the large exclusion of delayed-fluorescence,prompt-phosphorescence, and colorimetric signals. Alternatively, underother conditions the devices may be used to preferentially detectdelayed-fluorescence and prompt-phosphorescence overdelayed-phosphorescence and colorimetric signals. However, it is clearthat these selective detection events, although useful in their ownright, are advantageously greatly enhanced when used in conjunction withother images that contains additional information. For example, pairwisecombinations of any of the image analysis techniques described hereinmay be used. Multiple images may be fused that are collected for thedetection of any of the signals. In some contexts, this process may beconsidered as signal averaging, which generally increases the signal tonoise ratio at a rate equal to the square root of the number of signalsaveraged.

One of ordinary skill in the art will also recognize, based upon theteachings of this specification, that an electronic global shutter may,in some embodiments, be used to produce time dependent emission data(non-steady state photon emission data). In some such embodiments, thecycle time (the time over which each image is exposed and read) is fastenough to capture differences in a non-steady-state emission. Selectionof an appropriate excited state lifetime of an emissive species with aphoton detection device operating with a global shutter may be usefulfor producing a non-steady-state photon emission signal in accordancewith some embodiments described herein. In some embodiments, a globalshutter based device may achieve the time resolution of thenon-steady-state photon emission detection through multiple images thatare read separately. In some embodiments, suitable delays between theturning off of a pulsed excitation and an image being collected underglobal shutter conditions is used to create the time information. Insome embodiments, only a single delay is used. In some embodiments,multiple images are collected at one or more different delays.Electronic global shutters may also be used, in some embodiments, todetect non-steady-state emission produced by a modulated excitation. Insome such embodiments, the global shutter device will detect emissionsat different points in time relative to the modulated emission. Thedelayed emission may be detected, for example, as a result of itsdifference in phase from the excitation waveform or a difference inwavelength from the prompt fluorescence, reflection, and/or scattering.

Optical signals may also be added to biological diagnostic assays thatprovide additional information that may be read using the digital cameraof a smartphone. For example, temperature sensitive emissive materialsmay be added to indicate the temperature at which the assay wasperformed and/or indicate that the assay has not been exposed todetrimental hot or cold conditions. This information can provide keyinformation about the expected accuracy of the assay. In some cases, itmay be useful to track or validate the authenticity of the assay toprevent fraud or misuse. In this case an optical code that encodescomplex information for authentication may be included. In some cases,internal controls for facile calibration or fiducial registration of theassay may be included. For example, emissive materials of knownperformance may be incorporated into the assay as an internal referencefor results calibration.

To increase the throughput of biological assay results interpretation,multiple assays may be simultaneously imaged and analyzed. For example,simultaneously imaging and analyzing four LFAs can quadruple thethroughput resulting in significant time, labor, equipment, and costsavings; particularly in time sensitive and/or resource limitedenvironments.

The fusion of various images described herein may advantageously provideimproved sensitivity and fidelity in biological diagnostic assays. Insome cases, this data may be collected in rapid succession e.g., tominimize the effect of physical movement or the lighting conditions thatoccur during the course of a measurement. The composite data resultingfrom the fusion of signals from different optical elements or the sameoptical element measured multiple times provide improved signal to noiseratios as compared to some conventional techniques. In some cases, asmartphone or digital camera is configured to read an assay without anyadditional light source or optical filters. In some embodiments, imagesare collected using ambient light and/or with illumination by thesmartphone's or digital camera's flash (onboard white light LED). Theflash, which is generally designed to provide white light, may be usedto excite emissive materials with white light excitable chromophores andone or more of the previously mentioned classes of materials. Excitationby the flash may be performed in steady-state wherein images are takenunder the conditions of continuous illumination, with this methodpreferred for collection of colorimetric and prompt-fluorescence signalsfrom a biological diagnostic assay. By pulsing or modulating the flashintensity in time and applying the rolling shutter or video capturecapabilities of the smartphone, digital camera or other optical imagingdevice, delayed-fluorescence, prompt-phosphorescence, ordelayed-phosphorescence may be detected.

For example, in some cases, it may be advantageous to make use of anexternal light source such as a light emitting diode (LED) to excite theemissive species. This light source may be used in either steady-statemode or to create time sequenced detection in pulsed/modulated mode. TheLED may be selected to generate ultraviolet light that is higher energythan the light output from a smartphone or digital camera's flash. Theultraviolet light may be intrinsically excluded from detection becauseof the lack of transparency of the optical elements to this wavelengthof light. The excitation light used to excite the prompt-fluorescencemay be removed from impinging on the detector by use of a filter. It ispossible that multiple LEDs may be used to selectively excite differentemitters and these light sources may be independently operated in asteady state, pulsed, or modulated fashion.

In addition to filters, polarizers may be used to create specificsignals, in some embodiments. Polarizers may be used in conjunction withthe excitation to give polarized excitation and additional polarizersmay be placed between the assay and the detector for selective detectionof different polarizers. The combined use of polarizers on both theexcitation and detection elements may be used and the relativearrangement of the polarizers may be used to create improved signalcontrast and eliminate stray light (optical noise). As a result,polarizers may be used to create enhanced signal to noise and henceimproved sensitivity in biological diagnostic assays. Polarizers mayalso be used to eliminate stray light and allow for improved performancein assays performed under ambient light. The degree of depolarization ofemissive species may also be used in biological diagnostic assays. Inthis case a polarized excitation is applied and the degree to which theemitted light has the same polarization provides relevant information.Depolarization can occur as a result of motions of the emissive materialprior to emission or as a result of energy transfer between multipleemissive species. The degree of depolarization may also be related tothe lifetime of the emissive material.

The excited state lifetimes of the emissive materials used in thisinvention can vary as a function of their environment. The rollingshutter method when paired with different time synchronized opticalexcitations may be used to reveal information about the absolute orrelative excited state lifetimes of the emissive materials. Given thatthe excited state lifetime is a function of the material's localenvironment, there may be changes in this value as a result of proximatebiomolecular recognition processes. In some cases, a biomolecularrecognition event can trigger the formation of a new complex. Such anevent can yield new emissions that are distinct in both the intensity asa function of wavelength as well as the lifetime. It is also common thatchanges in the solvation of an emissive material that are associatedwith a biological assay give rise to changes in lifetime. For example,many emissive materials have excited state lifetimes that change inpolar aqueous environments relative to nonpolar environments.

The same hardware can optionally be used for both steady-state andtime-gated (non-steady-state) measurements by firmware and/or softwarechanges.

In delayed-fluorescence, prompt-phosphorescence, anddelayed-phosphorescence, there may be, in some cases, optimal parametersfor reading biological diagnostic assays. Optimization in these casesmay involve creating a set of parameters that maximizes the signaland/or minimizes (suppresses) the background (e.g., including straylight) signals. These parameters generally depend on the particularassay and conditions under which the reading is conducted. When deployedon a smartphone a colorimetric signal may be used to provide informationthat directs the user to orient the smartphone in a particular mannerrelative to the assay to generate a desired signal. In some cases, thisinformation, which may be contained in a logo, QR code, or bar code onthe assay informs the smartphone about the optimal camera settings suchas shutter speed (exposure time) and/or sensitivity (ISO) setting andthe excitation profile. In some cases, the phone may performmeasurements that rapidly explore a range of values for the shutterspeed/ISO and the type/duration of excitation to be used.Computationally, the smartphone may be used to determine imagingconditions that produce desired signals (e.g., by providing highdefinition/contrast, the rejection of artifacts and stray light, andproducing bright emissive signals). It may be that the data collectedduring this survey is adequate and optimal signals may be extracted frommany images. It may be that all images are fused together, in someembodiments, such that only a fraction of the images are used to createthe measurement. It may also be the case that guided by a quick surveymethod, computational methods yield imaging parameters that configurethe smartphone to make subsequent measurements using a particular set ofparameters to create an optimal measurement. For example, this may beused to determine if the assay is moved away from a bright interferinglight source or change the time over which each image is collected bythe detection chip (shutter speed or exposure time), or how best toconfigure the excitation. The latter may be pulsed light flashes or afrequency modulated method. In some cases, the smartphone may instructthe user to seek conditions that limit ambient light. This may beaccomplished, for example, by going into a dark room or closet or usinga dark cover over the camera and assay to eliminate light. The lattermay comprise a dark cloth, piece of black plastic, or a box capable ofpositioning the camera relative to the assay while blocking stray lightfrom interfering with the measurement. The latter may comprise adisposable element provided as part of product packaging.

In some cases, it may be advantageous to incorporate some or all of thediagnostic reader components or design features into the productpackaging. These components can include, but are not limited to: UV,blue, or white light LED(s) for diagnostic assay excitation or statusindicator functions such as power or diagnostic read-time alerts;optical filters, polarizers or lenses; a battery; and supportelectronics/PCB. In preferred embodiments, product packaging for thediagnostic assay may be used to block stray light and position thesmartphone's camera relative to the diagnostic assay during resultsacquisition by simply resting the smartphone on top of the box. In oneparticularly preferred embodiment, the interior of the product packagingoptionally includes an LED for excitation; optical filter(s), lens(es)or polarizer(s) for excitation and emission light optimization; alightweight disposable battery; a PCB incorporating the supportelectronics; calibration, authentication or fiducial markings; andphysical feature(s) such as guardrails to reliably orient the diagnosticassay relative to the imaging optics. In this preferred embodiment, theexterior of the product packaging optionally includes printed productinformation; authentication or tamperproof features; alignment featuressuch as printed outlines of different smartphone make and models; andperforated regions that may be removed based on the smartphone make andmodel to enable the smartphone's camera to image the diagnostic assaylocated in the interior of the product packaging. The product packagingcan either be disposable or reusable. Optionally, a solar cell may belocated on the product packaging exterior to supply power and eliminatethe battery requirement.

In some embodiments, an enclosure is configured to receive a consumerelectronic device (e.g., smartphone). For example, the enclosure maycomprise one or more features which correspond to the shape, size,and/or configuration of the consumer electronic device. In someembodiments, the features may be adjustable (e.g., such that differentconsumer electronic devices may be integrated with the enclosure, suchthat the positioning of the consumer electronic device may be adjusted).The enclosure may receive the entirety of the consumer electronicdevice, or only a portion of the consumer electronic device. Forexample, the enclosure may be adapted and arranged such that it enclosesthe image sensor and/or source of electromagnetic radiation of theconsumer electronic device.

In some embodiments, the enclosure comprises a source of electromagneticradiation. In some embodiments, the source of electromagnetic radiationis a component of the enclosure. In some embodiments, the source ofelectromagnetic radiation is a component of the consumer electronicdevice. In some embodiments, the source of electromagnetic radiation isin communication with the consumer electronic device (e.g., via one ormore of circuitry, electrical communication, processor(s), and thelike). For example, the source of electromagnetic radiation may receivea signal from the consumer electronic device such that electromagneticradiation is produced. In some embodiments, a user interacts with theenclosure such that the source of electromagnetic radiation produceselectromagnetic radiation.

In some embodiments, the enclosure is configured to position theconsumer electronic device relative to an article (e.g., a diagnosticassay, an article associated with an emissive species). In someembodiments, positioning the consumer electronic device comprisespositioning a sensor of the consumer electronic device, such that it candetect and detectable emission from the article (or emissive species).

In some embodiments, at least a portion of the enclosure is closed oncethe consumer electronic device is positioned. For example, in someembodiments, upon receiving the consumer electronic device, theenclosure is configured such that light external to the enclosure isprevented from interacting with a portion of the article, with theemissive species, and/or with the sensor. In some embodiments,preventing external light from interacting with the sensor means thatthe sensor will generally only receive electromagnetic radiationgenerated by the source of electromagnetic radiation and/or emitted bythe emissive species. Advantageously, a closed enclosure may reduce oreliminate background signals and/or noise, and/or prevent exposure ofthe emissive species to undesired electromagnetic radiation.

In some embodiments, the enclosure is configured to receive an assaycomponent (e.g., a lateral flow assay, a vertical flow assay, a chip, acassette, a cartridge, an article containing a sample). Exemplaryenclosures and exemplary components thereof are shown in FIGS. 14A-14F.In some embodiments, the enclosures are designed such that a user mayinteract with the consumer electronic device while performing an assay.Enclosures and/or assays may be useful in conjunction with variousapplications described herein including, but not limited to,diagnostics, authentication, detection, identification, purity, andquality control.

In some embodiments, the embodiments described herein are used inconjunction with an integrated sampling and/or analysis cassette. Insome embodiments, the methods and systems described herein may be usedto analyze s sample provided on the sampling and/or analysis cassette.In some embodiments, all components needed for sampling and analysis areprovided in a kit. For example, as shown in FIG. 14F, the kit maycomprise, in some cases, an integrated cassette, a sample collectioncomponent (e.g., a swab, a collection reservoir, a vial), an optionaladapter for a consumer electronic device (e.g., a smartphone), and anoptional tray (e.g., for sample prep). In some cases, instructions foruse of the kit may be provided (e.g., on one or more components of thekit such as the tray).

The combination of different images generally allows for additionalinformation to be stored with the results of an assay. This may includethe individual assay, type of assay, the location where the assay wasconducted, and the time of the assay.

In an exemplary embodiment, delayed-phosphors based on europium chelatesmay be used in LFAs, with stand-alone readers to read such assays.Smartphone readers using the methods described herein may be configuredto read these assays. In the case that the europium cannot be optimallyexcited using the white light flash (onboard LED) of the smartphone'scamera, a supplemental light source that has shorter wavelengthexcitation frequencies (UV or blue light) is used in conjunction withthe smartphone.

In some embodiments, the combination of an off the shelf smartphone andblue LED is a useful alternative compared to a dedicated reader.Smartphones have considerable computation power, may be connected to thecloud for additional computational resources and/or results reportingpurposes, provide spatial-temporal data, and/or may be configured tocapture and read other imagery (QR codes, text, bar codes). A smartphonesystem may also be deployed more broadly and rapidly. The applications(apps) that convert the smartphone to a lateral flow reader can beeasily downloaded and upgraded on the phone. If pairing with an externalLED, the devices may be readily paired with the smartphone synchronizingwith the pulsed or frequency modulated LED excitation. The rollingshutter along with the time synchronized excitation may be used toeliminate or identify noise from stray light that can be compensated forin the measurement through baseline correction. In some embodiments, thesmartphone need not rely on a blue LED excitation and will be able toread the assay using its onboard white light flash. Advantageously, thesmartphone synchronizing with the pulsed or frequency modulated LEDexcitation may not, in some cases, require that the data acquisition andthe excitation be synchronized, but that the relative times can bededuced, and hence synchronized, computationally from the data/imageacquired.

The smartphone reader may provide biological diagnostic assays to beread more widely than custom hardware and may serve, in someembodiments, to enable deployment scenarios including point-of-care,near-home, and at-home testing with facile cross-referencing of theresults.

In some embodiments, an optical method is described that may be used tomonitor the thermal degradation of a product. In some embodiments, asmartphone may be used to make a determination of the degree of thermaldegradation, which will be a function of the cumulative time andtemperature exposure. In some embodiments, the optical methods may beused to determine a peak temperature. In some embodiments, themeasurement is used to determine if a product has exceeded a recommendedthermal exposure. These determinations may be used, in some cases, incombination with other information such as authentication of theproduct, its date of manufacture, or exposure to light.

Advantageously, some embodiments described herein may provide greaterprecision and/or are readily integrated with information or sensing byoptical interrogation of a product, e.g., as compared to traditionaltime temperature indicators and/or dosimetric labels. For example,considering the nature of degradation processes and the statisticalnature of the thermal activation that control the degradation processesin materials, there may not be a clear linear relationship between theproduct of temperature and time and the degree to which a product isdegraded with traditional methods. In some embodiments described herein,advantageously, monitoring other thermally activated processes that maybehave as an “integration device” to quantify the thermal exposure maybe used. Without wishing to be bound by theory, these processes need notbe the same types of process as those that lead to the degradation ofthe product, but may be correlated to the degree of thermal degradationand provide a measure thereof. As such, in some embodiments, thecomponents and methods described herein provide a temporal thermalprofile which corresponds to the quality (and/or authentication) of aproduct.

In some embodiments, the components and methods described herein usethermally activated changes in the delayed emission of materials todetermine temperature exposure for monitoring the thermal degradation ofproducts. The delayed emission, defined as light emitted from an excitedmaterial after 10 nanoseconds, advantageously provides for thecollection of high-fidelity signals that may be read by any detectorsystem (e.g., capable of differentiating light emitted after 10nanoseconds, from light emitted in less than 10 nanoseconds, capable ofdetecting a non-steady state emission). In some embodiments, the lightis collected at least 1 microsecond after the emissive material isexcited and, in some cases, the excitation light has been removed. Insome embodiments, a smartphone (and/or component associated with thesmartphone) may be used as the detector of the delayed emission, and isdescribed in more detail below. The delayed emission from the designedemissive material system may, in some cases, report on the thermalhistory of a product (and, in some embodiments, in multiple ways).Responses to thermal exposures may include, for example, opticalabsorption and emission wavelength changes, new physical patterns ofoptical absorption and/or emission, changes in the emissive lifetimes,changes in intensities, and/or combinations thereof. The emissivesignals may, in some embodiments, be used in conjunction with otheroptical codes including methods to allow for serial tracking,authentication, recording expiration dates, determining total lightexposure, etc.

In some embodiments, a composition comprises an emissive speciesconfigured to be associated with an article. In some embodiments,excitation of the emissive species produces a detectable signal (e.g.,having one or more delayed emissions of greater than or equal to 10nanoseconds). As described herein, in some embodiments, the detectablesignal corresponds to a temporal thermal history of the article.

In some embodiments, a label comprises one or more emissive species. Insome embodiments, the label is associated with an article. For example,labels described herein may be useful in determining the temporalthermal history of an article. In some embodiments, the label comprisesan emissive species optionally having one or more first detectabledelayed emission(s) of greater than or equal to 10 nanoseconds induration corresponding to a first temporal thermal history of theemissive species. In some embodiments, the label comprises one or more,two or more, three or more, four or more five or more, six or more,eight or more, ten or more, twenty or more, or fifty or more emissivespecies (e.g., each corresponding to a temporal thermal history).

In some embodiments, the detectable delayed emission, if present uponexcitation of the first emissive species, corresponds to identificationof the emissive species being exposed to the temporal thermal history.

In some embodiments, as described herein, the label is configured to beproactively added to an article, such that the label provides a temporalthermal profile of the article.

In some embodiments, an excitation component is configured to excite,using electromagnetic radiation, an emissive species such that, ifsingle or multiple emissive species, or their precursors, were exposedto a temporal thermal history, produces a detectable delayed emission(e.g., non-steady-state emission) of greater than or equal to 10nanoseconds. In some embodiments, a detector is configured to detect atleast a portion of the detectable delayed (e.g., non-steady-state)emission. The detector may be, in some cases, associated with theexcitation component.

As described in more detail below, in some embodiments, the detectorcomprises a rolling shutter mechanism.

In some embodiments, the detectable delayed emission comprises a peakintensity, emission lifetime, absorption wavelength, and/or emissionwavelength.

In some embodiments, the response to excitation involves a change in thewavelength of the absorption or emission related to the delayedemission. In some embodiments, the response involves a change inintensity of a detectable signal. In some embodiments, the responseinvolves a change in the delayed emission lifetime. In some embodiments,the response involves the creation of a new delayed emission. In someembodiments, the response involves the removal of a delayed emission. Insome embodiments, the response involves two components combining toproduce or remove a delayed emission.

In some embodiments, the response involves a matrix that changes itsphysical properties to create changes in the delayed emission signal. Insome embodiments, the response involves the diffusion of one or morematerials to create changes in the delayed emission signal. In someembodiments, the response involves a matrix that undergoes a phasechange that produces or changes the delayed emission signal. In someembodiments, the response involves chemical reaction to produce thedelayed emission signal. In some embodiments, the response involveschanges in aggregation to produce or change the delayed emission signal.In some embodiments, the response is produced by an enhancement inenergy transfer from an antenna molecule or polymer to a delayedemission component. In some embodiments, the response produces a patternfrom the delayed emission signal. In some embodiments, the response isproduced from materials that are safe for humans consume.

In some embodiments, the label is produced by the deposition of secondmaterial onto a delayed emission material in order to produce a systemcapable of displaying a temporal thermal history.

In some embodiments, the composition is produced with componentsproximate to each other. In some embodiments, one of the components ofthe composition, label, and/or system is fused onto or into glass. Insome embodiments, components are separated physically from each other.

In some embodiments, the composition, label, and/or system is producedby spray deposition, ink jet printing, printing, or lamination.

In some embodiments, the delayed emission has a lifetime greater than 10nanoseconds, greater than 100 nanoseconds, greater than 1 microsecond,greater than 100 microseconds, or greater than 1 millisecond. In someembodiments, the delayed emission has a lifetime less than 10milliseconds, less than 1 millisecond, less than 100 microseconds, lessthan 1 microsecond, or less than 100 nanoseconds. Combinations of theabove-referenced ranges are also possible (e.g., greater than 10nanoseconds and less than 10 milliseconds). Other ranges are alsopossible.

In some embodiments, the delayed emission species contains a metal ion.In some embodiments, the delayed emission species is an organicmolecule. In some embodiments, the delayed emission species is ananoparticle. In some embodiments, the delayed emission species is acrystal. In some embodiments, the delayed emission species is amicroparticle. In some embodiments, the delayed emission species is anorganic molecule containing heavy atoms.

In some embodiments, excitation of the emissive species is accomplishedby a light source with modulated intensity at different frequencies. Insome embodiments, excitation of the emissive species is accomplished bya light flash or a laser pulse.

In some embodiments, the detector (e.g., reader) is a smartphonecomponent. In some embodiments, the detector is a component of a streakcamera. In some embodiments, the detector is a component of a devicecapable of selectively detecting a delayed emission. In someembodiments, the detector is a component of a device capable ofselectively detecting a delayed emission in a complex environment withnon-delayed emission, ambient, and reflected light present. In someembodiments, the detector is a component of is a device capable ofselectively detecting a delayed emission and is also capable ofdetecting prompt-fluorescence, ambient, and reflected/scattered light.In some embodiments, the detector is capable of detecting patterns ofdelayed emission to produce information about a thermal or coldexposure. In some embodiments, the detector is capable of detectingpatterns of delayed emission as well as patterns fromreflected/scattered, ambient, or non-delayed emission to produceinformation about a thermal or cold exposure. In some embodiments, thedetector is capable of integrating information of a thermal or coldexposure with other information optically encoded on the product.

In some embodiments, the detector comprises a CMOS imaging chip.

In some embodiments, the detector is configured to use a rolling shuttereffect to collect the delayed emission data.

In some embodiments, the detector is configured to use a global shutterto collect images that may be sequenced at various times (e.g., withregard to a non-steady-state excitation).

In some embodiments, the temporal thermal history is the cumulativeamount of time that an article (and/or label and/or composition)experiences a particular temperature or range of temperatures and thatshorter times at higher (or lower) temperatures could be equivalent tolonger times at less high (or less low) temperatures.

There are a number of ways to translate a thermal exposure into adetectable change in the delayed emission in this invention. For manyemitters (emissive materials) the emission intensity is generallyreduced with increasing temperature. Without wishing to be bound bytheory, this is generally a result of the internal dynamics includingmolecular motions wherein rotational, vibrational, rocking, aggregation,collisional, and/or combinations of these processes cause a material torelax faster from an excited state to a ground state without giving offan optical photon. These thermal relaxation processes are collectivelyreferred to as a non-radiative processes and result in the relaxation ofan excited material to its ground state (non-excited form). Innon-radiative processes the energy is often dissipated as local heatthat is absorbed by the local environment. The rate at which a materialundergoes a non-radiative process may, in some cases, depend on theenvironment. For example, if the internal dynamics (motions) enhance thenon-radiative rate then an environment that restricts a material'sphysical dynamics, will affect the rate the non-radiative processes. Anincreased rate of non-radiative relaxation as a result of a particularthermal history may produce a decreased intensity of an emission signal,but may be used to create a time temperature indicator (TTI) is todetect changes in the emission lifetime of the emissive materials. Thisis because the intensity of an emission is dependent on the amount ofmaterial initially excited and will at a minimum require a referencesignal. It is also possible that other secondary processes not relatedto the TTI response will cause degradation of the emissive materials togive a non-emissive material and thereby lower the emission intensity.Monitoring of the emission lifetime may, in some cases, be independentof the amount of the active emissive material and the degree to which itis excited. The emission lifetime is generally related to the time thatthe molecule remains in its excited state. The emission lifetime is, insome embodiments, inversely related to the additive rates of allnon-radiative and radiative processes. Increases in either thenon-radiative or radiative rates of a dye may, in some cases, give areduction in a dye's emission lifetime. Conversely decreases innon-radiative or radiative rates may, in some cases, increase anincrease a material's emission lifetime. However, the emissionintensities and lifetimes may not give the same information. Forexample, a faster emission rate may, in some cases, allow for brighteremission and still cause a reduction in a material's lifetime.Alternatively, a faster non-radiative rate may, in some cases, reduceboth the brightness of the emission and the material's lifetime. As aresult, the emission intensity and emission lifetime may, in some cases,in some cases vary independently and other information may, in somecases, be necessary to produce a useful TTI that may, in some cases, beimparted by having multiple delayed emissions from different emitters orlocations on a product or its packaging.

An additional advantage of lifetime sensing is that it may, in somecases, be used to remove interfering fluorescent signals from materialsfound in products and their packaging that typically display lifetimesless than 10 nanoseconds from the time wherein the material is put in anelectronically excited state. In some cases, it may be advantageous toexclude emissions with lifetimes that are less than 100 nanoseconds fromthe time of excitation, and in yet other cases it may be advantageous toexclude emissive signals that are less than 1 microsecond from the timeof excitation. However, some embodiments described herein are notintended to be limited as such.

By detecting longer lived emissive signals, it is possible to removeintrinsic background emission and depending upon the context of themeasurement and the product, measuring the emission at different timeperiods may be desired. Many products have intrinsic fluorescence, andit is typical to add emissive dyes to products to make them appealing.However, by detecting delayed emissions, only selected emissivematerials are being recorded. It is also clear that more informationmay, in some cases, be produced by having multiple emissive signals withdifferent emission colors and lifetimes or changes thereof. For example,it may be desirable in some TTI applications to have a high-performancereader that may, in some cases, make use of very short-lived signalsthat are only slightly longer than 10 nanoseconds. In other applicationsthat involve consumers it will be best to use signals that may, in somecases, be read by a smart phone for TTI. In some embodiments theemissive signals of interest may, in some cases, be patterned to createadditional TTI information and in yet other cases the emissive signalsmay, in some cases, be used in coordination with other optical patterns,including trade-marked logos, QR codes, bar codes, and pictures orpatterns on a products packaging.

Smart phones may, in some cases, be used to read TTI devices based on adelayed emission. In some embodiments, pulsed or modulated excitationlight, is used in conjunction with detection using the rolling shuttereffect in the smartphones camera unit. In some cases, it will besufficient to detect only light coming from a delayed (e.g.,non-steady-state photon) emission. In other cases, capturing images ofdelayed emission will be useful and the rolling shutter mechanism may,in some cases, be used to resolve both the spatial position and theemission lifetime.

An emissive species may have any suitable structure. The emissivematerial may, in some cases, be any suitably emissive material includingpolymers, waxes, pigments, metal complexes, main group complexes,lanthanide complexes, inorganic oxides, inorganic sulfides, inorganicsalts, metallo-organic molecules, organometallic molecules, organicmolecules, organic semiconductors, inorganic semiconductors, halogenatedorganic molecules, supramolecular complexes of multiple molecules,molecular aggregates, nanoparticles, or nanostructured materials. Thoseskilled in the art will recognize, based upon the teachings of thisspecification, that there are many emissive materials that fall in thesegeneral classifications as well as others that will have the necessaryoptical properties to be used in this invention. The excitation of thematerial may, in some cases, be performed by light, by electricalmethods, or by chemical methods, as described in more detail below. Theexcitation may be performed in a fashion that may, in some cases, beused to determine the lifetime of the emissive material. For example,optical excitation of a flash may, in some cases, be used and theemission collected over one or more time periods thereafter.Alternatively, excitation may, in some cases, be used provided that theintensity is modulated. In general, frequencies (Hertz=cycles/second)over which the light intensity is modulated may correspond cycle timesthat are similar or shorter than the lifetime of the emissive signal. Itmay be advantageous to use multiple different frequencies for a TTImeasurement.

In some embodiments, the emissive species is a chemical and/orbiological species. In some cases, the emissive species is afluorophore, a phosphor, or a thermally activated delayed fluorescence(TADF) molecule or molecular complex. In some embodiments, the emissivespecies is configured to bind to a chemical and/or biological species.

The method of construction of this TTI invention or equivalent thermalexposure measuring device requires one or more emissive materials ormaterials that may, in some cases, transform into emissive materials andsupporting compositions that may or may not be active. In some cases,the supporting composition will include a cofactor, which is a material,which may, in some cases, also be emissive, that modulates the lightcoming from the TTI. The cofactor may, in some cases, change thematerials emission lifetime, optical absorption characteristics,emission intensity, or spatial patterning of the emission from the TTI.In some cases, a cofactor is required to create the emissive materialthough a reaction or association. In some cases, structuring of thefabricated materials that provide for the TTI indicator is important.For example, it may be possible to have emissive materials physicallyseparated initially from the cofactors. In some cases, the relativeconcentrations of the emissive materials and various cofactors will beimportant. In other cases, variations in material compositions andphysical separations will be used to create unique patterns that provideTTI information. In other cases, the physical characteristics of thematerials will be important such as their melting/freezing point orglass-transition temperature (T_(g)). Fabrication methods to accomplishthese features include lamination, screen printing, spray coating,inkjet printing, roll to roll methods, or anyway that a solvent ofdispersion may, in some cases, be applied to a surface.

The context of how an emissive material or an emissive materialprecursor is positioned in a TTI composition and the degree to whichthermal exposures change the properties through the mechanicalproperties of the matrix, chemical reactions, concentration, and spatialdiffusion may, in some cases, be used independently or in combination todetermine a thermal exposure. In some embodiments, there is detectablechange in the delayed emission. In some cases, thermal exposures to acomposition create new delayed emissions and in other cases delayedemissions are reduced or removed by thermal exposure. In other cases,the wavelengths where the emissive species absorb or emit light changein response to a thermal exposure to create a TTI. In other cases,changes in the lifetime of the emissive species may, in some cases, beused to create a TTI. In other cases, special locations are selectedwhere emissive species will change to create a TTI. In yet other cases,combinations of any or all of these respective effects may, in somecases, be used to create a TTI. The organization of the emissivematerials and other cofactors in a composition is critical to produce aresponse to a thermal exposure that meets the requirements of a product.The temperatures of interest range from below −80° C. to above 100° C.with many anticipated applications ranging from −20° C. to 60° C. Thematrix may, in some cases, be a single material or contain multiplecomponents. For example, the matrix may, in some cases, be composed of awax, polymer, inorganic oxide, silica, gel, a fluid, natural fibers,fatty acid or ester, or combinations thereof. The different activeelements (emitters, cofactors and their precursors) may, in some cases,be uniformly distributed in the matrix or display compositionalvariations either laterally of vertically with regard to a surface. Inmany cases, different materials will be co-fabricated to form stratifiedcompositions. The physical separation of different elements in a matrixmaterial may, in some cases, allow for responses to occur if materialsmay, in some cases, be made to diffuse with thermal exposures. Thematrix in some embodiments will display a change in its mechanicalproperties, which could include a phase change, softening, orinterdiffusion (mixing) with other materials in the composition inresponse to a thermal exposure. In other cases, the matrix is simply amedium that other processes, including chemical reactions and diffusion,occur under thermal exposure. In some cases, different components thatcome together to create a TTI may, in some cases, be produced bylamination of one or more layers onto a product. In other cases, thecompositions that produce a TTI may, in some cases, be printed andpositioned proximate to each other. The physical dimensions and spatialpatterning of the different elements of the composition may, in somecases, used to give a specific TTI. For example, when a thermal exposureallows for emissive species, emissive precursors and/or cofactors todiffuse over a given distance, the different elements need to bepatterned to produce a readable response relevant to the targeted TTI.The distance over which diffusion occurs will be highly dependent on thethermal exposure. In most cases diffusion distances will increase withhigher temperatures and longer durations. The physical spacing andpatterns of the new emissive characteristics (lifetime, wavelength,intensity changes) generated as a result of a thermal exposure may, insome cases, be used to produce a TTI. In some cases, the pattern ofemissive species may, in some cases, also be used to authenticate aproduct. In this method, measurement of the characteristics of theemissive species provides an identification code that is not easilyreproduced.

The dynamics and mobility of a material may, in some cases, beinfluenced by its local environment and hence the properties of thematrix. Increased rigidity may, in some cases, reduce degrees of freedomin a material such as rotations about chemical bonds, bending motions,wagging motions and collisions with other molecules. In some cases, amolecule will have a reduced non-radiative rate in a more rigidenvironment as a result of reductions in these processes. This reductionin the non-radiative rate will yield an increased emissive lifetimerelative to a more dynamic state. In some other cases, a material may,in some cases, be trapped in a particular configuration in a rigidenvironment and have an emission behavior with a different lifetime,wavelength, or brightness than it will have in a less constrained lessrigid environment. In some cases, the thermal process will result indiffusion of materials that give rise to changes in the emissionlifetime. It is also possible that a material may, in some cases, betrapped in a non-equilibrium higher energy state or conformation in amatrix such that it emits light at a different wavelength, lacks adelayed emission, is non-emissive, has a very different excited statelifetime, or combinations thereof. A thermal exposure may, in somecases, allow the material to relax to a lower energy state and givechanges in its emission efficiency, excited state lifetime, wavelengthsof emission and absorption, or combinations thereof.

A material or matrix material may with thermal exposure diffuse (move)from one micro-environment/phase to another or two separate phases may,in some cases, become one. In other cases, increased temperature may, insome cases, result in phase separation. In other cases, the increasedtemperature may, in some cases, cause solid phases to be melt intoliquids. In other cases, a polymer or solute may, in some cases, bedissolved in a solution that precipitates with a thermal exposure. Sucha polymer or solute has what is known as an upper critical solutiontemperature and there are a number of examples in water. For example,phenol and water have an upper critical solution temperature and manycopolymers of N-isopropyl acrylamide are known to have a range of uppercritical solution temperatures. The matrix that creates themicro-environments may, in some cases, have compositional gradients orseparate domains of different materials and be a wax, fatty acid orester, polymer, gel, paper, fluid, or other solid. For example, anemissive material may, in some cases, be positioned in a higher rigiditymatrix and with thermal activation a softening material may, in somecases, diffuse into the rigid matrix and cause it to become less rigid.There are many potential matrix materials that will soften as a resultof thermal processes, such as changes in the materials conformation,reduction of internal stresses in the matrix, disruption of physicalinteractions, or even thermal breaking of bonds. If the changes in thematrix materials allow for the internal dynamics of the emissivematerial to be enhanced then a decrease in the emissive lifetime may, insome cases, be detected.

It is also possible that thermal exposures may, in some cases, give riseto an increase in the effective rigidity of the local environment aroundan emissive material and thereby decrease the rate of non-radiativeprocesses. In these situations, the emission lifetime may, in somecases, increase. For example, a matrix material may be captured in ameta-stable phase and transition to a more stable higher rigidity phasewith a thermal exposure. An emissive material may be dissolved in asolution or melt of a matrix material and rapid removal of solvent orrapid cooling may, in some cases, be used to create a higher energycomposite of the matrix and emissive material. This phase may, in somecases, be what is known as a solid solution wherein a solid containsrelative composition uniformity just as would be expected for asolution. Solid solutions may, in some cases, be stable indefinitely,and are in many cases thermodynamically unstable. Heating a solidsolution may, in some cases, allow for diffusion of the components andcause phase separation, reactions, and/or aggregation. In such a way thelocal environment around an emissive material may, in some cases, changein a dramatic way. If the two components crystallize it may, in somecases, result in a change in the local environment and change thedynamics, and hence the non-radiative rates, of the emissive material.It is also possible that a precipitation, cooling, or evaporationprocess creates a matrix that is characterized as having an amorphousglassy state, wherein there are some small local dynamics in the matrix.A glassy state may, in some cases, be stable for extended periods oftime, and for many materials either stress or thermal treatments may, insome cases, initiate crystallization. All of the processes justdiscussed may, in some cases, be used to create different dynamicenvironments around an emissive material that may, in some cases,produce measurable changes in the emissive lifetime that may, in somecases, be used to determine a product's thermal history.

There are abundant examples of materials that display changes inlifetimes as a function of their internal dynamics. One class ofmolecules are those that exhibit that is known as thermally delayedactivated fluorescence. The molecules shown display this process andhave reduced non-radiative processes, which gives longer lifetimes whenin a more rigid aggregated environment. (ref. Tsujimoto, H.; Ha, D.-G.,Markopoulos, G.; Chae, H. S.; Baldo, M. A.; Swager, T. M. “ThermallyActivated Delayed Fluorescence and Aggregation Induced Emission withThrough-Space Charge Transfer” J. Am. Chem. Soc. 2017, 139, 4894-1900,which is incorporated herein by reference in its entirety for allpurposes).

Without wishing to be bound by theory, a number of molecules havereduced non-radiative rates (longer lifetimes) when aggregated and thisgeneral process is known as aggregation induced emission. Key for thisinvention is that the emissive materials as well as the aggregatedemissive molecules have a lifetime over 10 microseconds. Longerlifetimes arise from thermally delayed activated fluorescence, emissionfrom a triplet excited state, or as a result of other dynamic equilibriawithin an emissive material. There are many materials that displaytemperature dependent emission (ref. Wang, X-Dong; Wolfbeis, O. S.;Meier, R. “Luminescent Probes and Sensors for Temperature” Chem. Soc.Rev., 2013, 42, 7834, which is incorporated herein by reference in itsentirety for all purposes). These materials have been utilized formeasuring a temperature at a specific time however, delayed emissivematerials have not been used to give an analysis of thermal exposurewith a single measurement as a TTI as is the subject of this invention.To monitor a thermal exposure, the emissive temperature sensitivematerials would require continuous monitoring or at least a number ofmeasurements over time. Such a method would not be appropriate for theanticipated applications of this invention wherein a product's thermalexposure (or its thermal history) will be determined by a singlemeasurement. For example, before administering a drug, a singlemeasurement that selectively detects emission lifetime(s) may, in somecases, be used to ensure that the product has not be subject to thermaldegradation. Materials and molecules that are known to be thermallyresponsive and have delayed emission are relevant to this invention,may, in some cases, be used to create TTI devices capable of determininga product's thermal history. In this case changes in the structure andproperties of the matrix material surrounding the emissive material may,in some cases, produce changes in the emissive lifetime, color, orintensity.

Energetic disorder caused by trapping materials in different high energystates may, in some cases, have a large effect on the ability of amaterial to transport energy over distances. Semiconductive/conjugatedpolymers are well known to behave as antennas to transfer energy overdistances. It has been found that these materials are more efficient attransmitting energy when they are in more regular states or when theyare placed into aggregated states. A TTI may, in some cases, be createdby using a thermal exposure to promote either a change in theorganization of the conjugated polymer to have a more planar structurewith greater delocalization or thermally induced phase separation of theconjugated polymer from a matrix. Most purely emissive conjugatedpolymers have excited state lifetimes less than 10 nanoseconds andincorporating a small percentage of a delayed emission component intothe polymer mixture, either by direct conjugation, as a pendant, or as aphysical mixture may, in some cases, be used to create a response.Either a transition of the conjugated polymer with a delayed emissivecomponent from a disordered to an ordered state, phase separation of theconjugated polymer delayed emissive component from the matrix material,or combinations thereof may, in some cases, be used to create a TTI.Dissordered states of the conjugated polymer and the emissive componentmay, in some cases, be generated by rapid quenching of a heated sample,by rapid dissolution caused by precipitation, by mechanical actions, byrapid evaporation of solvent, or combinations thereof. Additionally, itis possible that a delayed emission component or species capable ofcausing a delayed emission, may, in some cases, diffuse into a film of aconjugated polymer as a result of thermal exposure and also create a newdelayed emission signal to constitute a TTI.

Thermal processes may, in some cases, be used to create disorder inmaterials. For example, a polymer may be stretched such that its chainsare in a higher energy conformation. If the polymer is below atemperature wherein it may, in some cases, relax then it may, in somecases, retain the alignment that is associated with the polymer chainsfor extended periods. Chain alignment may, in some cases, be used toorient a dye or anisotropic nanoparticle with delayed emission that iswithin the stretched polymer host materials. As a result of this effectthe material will have an emission that is polarized and as a resultwill have angle specific optical properties such as reflection andabsorption. In a simple scheme, the emission may, in some cases, beattenuated by use of a polarizing component that limits light of thepolarization of the aligned material with the delayed emission. Withoutwishing to be bound by theory, with thermal activation the entropydriven relaxation of the host polymer will, in some embodiments, promotea more random orientation of the emissive material and the lightintensity may increase if the polymer has a decreased non-radiative ratein the disordered state. The host material may, in some cases, be manythings, including polyolefins, acrylates, vinyl polymers,polyarylethers, polysulfones, or the like that may, in some cases, bedrawn at select temperatures and align the guest delayed emissionmaterials. It is also possible to stretch an elastomeric polymericmaterial and cool it down in it to have it retain the orientation of thepolymer chains. Here again thermal exposure may, in some cases, be usedto erode the chain alignment and the alignment of the guest delayedemissive species. It is also possible that a bonding to a solid surfacemay, in some cases, be used to “hold” the host polymer in an alignedstructure. The bonding to the surface may, in some cases, be throughphysical linkages such as corrugations and roughened surfaces, throughelectrostatics, or through the application of an adhesive. In thesecases, a stretched material is applied to the article while undermechanical stress. Thermal exposures may, in some embodiments, weakenthe anchoring to the surface, or allow for realization of the stressedpolymer, and allow for the polymer chains to randomize and again reducethe alignment of the guest materials displaying delayed emission. It isalso possible that a delayed emissive materials that do not align in astretched polymer or have alternative alignments may, in some cases, beused to create TTI.

An alternative method to create aligned materials with delayed emissionin a variety of host materials by an active photolysis. For example,emissive materials may be activated (created) or deactivated (destroyed)by photolysis. In this case a higher energy (lower wavelength) lightsource will be used and polarized photolysis will activate or deactivatea population of the emissive materials that are aligned such that theyefficiently interact with the polarized light. In most cases the lightsource used to activate/deactivate the delayed emissive materials willbe in the UV part of the electromagnetic spectrum. This photolysistreatment will then create a delayed emissive species, but with thermalexposure the emissive material can randomize and loose its polarization.As with any of the schemes the choice of the host material and theemissive material will be key to create a TTI with the desiredperformance for an article.

Thermal processes may, in some cases, also be used to change the localconcentrations of emissive materials and other cofactors that affect theemissive lifetime. Thermally initiated crystallization and/or phaseseparation process from a solid solution may, in some cases, createcompositional heterogeneity. These may, in some cases, result inemissive materials and other cofactors concentrating in one phase, atgrain boundaries, at interfaces, and/or at surfaces. In some cases,these events may, in some cases, be used to create an emissive specieswith a longer lifetime. For example, two molecules that are componentsof a solid solution may, in some cases, be concentrated bycrystallization or phase separation to form an aggregate. The moleculesmay, in some cases, be the same or different and one of the moleculescould be an emissive material and the other may, in some cases, be acofactor. These processes may, in some cases, be used to producecompositions wherein upon illumination a new excited state complex may,in some cases, be formed known as an exciplex. When formed by moleculeswith different characteristics an exciplex may, in some cases, have whatis known as charge transfer character. This generally results in thepartial transfer of an electron from the donor molecule to the acceptormolecule. As a result of the low overlap of the respective orbitals onthe donor and acceptor molecules, these types of materials may, in somecases, display thermally activated delayed fluorescence. The delayedemission of these species will allow for use as a TTI in the context ofthis invention. In other cases, an emissive material and a quencher may,in some cases, be brought into proximity by a thermal exposure. Thequencher is a cofactor that modulates the lifetime of the emissivematerial. The quenching event may, in some cases, occur as a result of abinding event, such as a ligand binding a metal center, acid basereaction, hydrogen bonding, excited state proton transfer, metalchelation, electron transfer, and/or energy transfer. By the differentmechanisms described, emissive materials with changes in excited statelifetimes, emission intensity, absorption and emission wavelengths, orcombinations thereof may, in some cases, be generated. These delayedemission features, or lack thereof in the case of quenching, may, insome cases, be used in patterns that are designed to determine thedegree of a thermal exposure.

Diffusion of different materials into each other may, in some cases,affect the local environment around molecules in many other ways. If anemissive molecule is placed in an environment with proximate free spaceand is co-deposited with another material to give a phase separatedmixture. The environment may, in some cases, change by heating whereinmaterials will move in a way to fill the free space. For example, if thelower density part of the mixture contains an emissive dye/material thematerial may, in some cases, densify by the diffusion of anothermaterial to fills empty space proximate to the dye/material and therebyrestricts the internal movement of the emissive material. Morerestricted movement may, in some cases, reduce the rate of non-radiativeprocesses and give an increase in the emission lifetime. Alternatively,if the densification results in bringing a quencher molecule proximateto the emissive material, then the rate of the non-radiative processesmay, in some cases, increase and the lifetime may, in some cases, belowered. Emissive materials may, in some cases, form complexes withthemselves or with other molecules that may, in some cases, reduce theirinternal dynamics and result in decreased non-radiative rates. In thecontext of molecular emitters is also possible that a second dye or thesame dye may, in some cases, diffuse into a material having free volumeand form a complex with a guest dye. These processes may, in some cases,create species that have different lifetimes. The free volume in all ofthese situations may, in some cases, be created in a polymer or throughhost guest interactions. For example, polymers containing bicyclic ringsystems are known to promote free volume. Alternatively, emissivemolecules may, in some cases, form supramolecular host-guest complexesin macrocyclic cavity forming molecules such as calixarenes,cyclodextrins, cucurbit[n]urils, or pillaranes. If the cavities of themacrocycles are larger than the emissive guests, then other moleculesmay, in some cases, diffuse in under thermal activation and becomeproximate and change the emission lifetime. It is also possible that theemissive guests will be displaced by an incoming molecule under thermalactivation and once the guest is released it will have a differentemissive lifetime.

Thermally activated chemical reactions may, in some cases, be used tocreate changes in the emissive lifetime of a material or create a newmaterial with a delayed emission. Similar to what was previouslydiscussed, a material may, in some cases, contain multiple componentsthat upon thermal activation diffusion is enhanced and differentcomponents are brought proximate to each other. Beyond non-covalentassociations, the proximity of a cofactor may, in some cases, facilitatea chemical reaction. These reactions may, in some cases, be simple andcatalyzed when the cofactor is an acid or base. Alternatively, twoelements, which need not be emissive in their own right, may, in somecases, combine to form or destroy an emissive material with an emissivelifetime more than 10 nanoseconds for detection. For example, a reactionmay, in some cases, result in the coordination of an organic molecule toa metal center or metal nanoparticle. The coordination event may, insome cases, result in a dramatic change in the emission lifetime of theorganic molecule or alternatively the organic molecule may, in somecases, transfer energy into the local states of the metal ion andessentially serve as an antenna. For example, an Eu⁺³ metal center may,in some cases, coordinate with a ligand containing a nitrogen atom suchas a pyridine or phosphine oxide ligands that is also a chromophorecapable of capturing light. In this case the antenna ligand may, in somecases, transfer energy to the Eu⁺³ core states to produce a new emissionwith a lifetime greater than 10 ns. One who is skilled in the art willrecognize that there are many metal ligand combinations and interactionswith other heavy atoms from the main group, including iodides, bismuth,telluride, lead, etc., that may, in some cases, also promote differentlifetimes. For many applications it is important that the emissivematerials and the metal ions/heavy atom containing materials arenon-toxic. Non-toxic materials of note include dyes used as foodadditives. These materials may, in some cases, have intrinsic emissiveproperties and examples include Allura Red, Riboflaven, Fisetin,Quinine, Curcumin, Vanillen, Sunset Yellow,4,4′-bis(2-benzoxazolyl)stilbene, and Erythrosin B. The case ofErythrosin B is highly relevant as this molecule may, in some cases, beconverted between a longer wavelength emissive form and a colorless formwith base as shown.

For example, when Erythrosin B is in its neutral state thedelocalization is restricted and it not an effective chromophore.However, with deprotonation the spirolactone opens to create a veryeffective chromophore. The additional presence of iodines, which areheavy atoms, in the structure promotes intersystem crossing in theexcited state and this molecule has a long-lived excited state as aresult of the triplet state produced. For this system, base will createan emission with an extended lifetime that may, in some cases, bedetected and acid will deactivate the chromophore to remove the longlived excited state. Erythrosin B may, in some cases, for example bedeposited in a matrix material in its closed non-emissive form and abase capable of causing it to convert to the emissive state deposited inthe same or different matrix in a pattern on top of this material. Thematrix materials may, in some cases, be chosen to allow for diffusion ofthe base upon a prescribed thermal activation. The result of diffusionof the base to the molecule will create a new emission that has alifetime more than 10 ns that may, in some cases, be detected. Theduration and temperature of the thermal exposure may, in some cases, bedetermined by the degree of diffusion of the base and this feature may,in some cases, be determined by accessing the length of the diffusion ineither the lateral or vertical dimensions. The thickness of the matrixmaterials for both the dye and the base need not be the same and may, insome cases, have gradients in thickness. It is also possible that thediffusion will be determined by an additional layer of material that isinserted between the dye matrix and the base. It is also possible toprint the dye and base in an laterally offset geometry, in someembodiments. It is also possible to start with the colored negativelycharged form of Erythrosin B and quench the emission by reacting it withacid that may, in some cases, diffuse. It is also possible thatErythrosin B or its base form may, in some cases, actively diffuse uponthermal activation. The base and acid may, in some cases, be part of thematrix or covalently linked to the matrix. For example, one of thematrix materials may, in some cases, be a polymeric acid or polymericbase. The Erythrosin B and the acid or base may, in some cases, also beco-deposited on a product provided that each is in microparticle formwithin the matrix. In this way dispersions, potentially in a continuousphase of water, based on small micelles, or colloids may, in some cases,be deposited where the materials diffuse to give changes in lifetimeupon thermal exposure. There are other base catalyzed reactions,including elimination reactions that produce extended π-electronconjugation that may, in some cases, be used to create species withdelayed emissions. It should also be noted that all of the differentmechanisms suggested here may, in some cases, be applicable to manyother dyes and also need not be limited to acids and bases. Thesemechanisms may, in some cases, be applied to many of the generalmaterials sets described in this invention.

Purely thermal reactions may, in some cases, also be used to create newmaterials with delayed emissions. These processes may, in some cases, beas simple as dehydration. For example, Eu⁺³ species have reducedlifetimes in the presence of water. Hydrated metal complexes maycondense with dehydration to give new emissive complexes ornanoparticles. Hydrates of organic molecules such as aldehyde hydratesmay, in some cases, lose water to create or quench delayed emissionspecies. There are a variety of elimination reactions that may, in somecases, proceed thermally to create extended conjugation and cause achange in the optical absorption and emission wavelengths of delayedemission species. For example, molecules may, in some cases, eliminatehalide acids such as HBr, HI or HCl. Additionally, reactions such as theCope elimination may, in some cases, be used to create new double bonds.A variety of pericyclic reactions are possible, including thermalring-opening of cyclobutenes to create conjugated dienes, which whenintegrated with heavy atoms of some other material capable of creating adelayed emission may, in some cases, be used to create a compositioncapable of functioning as a TTI with this invention. Similarly, aDiels-Alder or retro-Diels-Alder reaction may, in some cases, be used tocreate a new emission. The Diels-Alder reaction is one of the mostcommonly used reactions in chemistry and there are abundant ways thatthis reaction may, in some cases, be used to create or destroy moleculesdisplaying a delayed emission.

The emissive materials may, in some cases, be purely inorganic andapplied to a product by way of a dispersion in water or other solvent.Purely inorganic materials may, in some cases, be considered ceramicsand are capable of withstanding high temperatures. For example, it ispossible that a precursor material may, in some cases, be applied to asurface with other materials such as surfactants to allow for precisionprinting of a pattern and then heated to high temperatures (>300° C.)wherein the organic materials are removed and with sufficient heating ona surface such as glass these materials may, in some cases, become fusedto the glass. The fact that the inorganic emissive materials do not meltmay, in some cases, result in nanoparticles or isolated elements thatare bound (fused) to the surface of a glass support. This process may,in some cases, be performed in conjunction with other particles thatform a pattern such as a bar code or QR code. A TTI may be formed, insome cases, using inorganic materials processed at high temperature if alaminate with an element designed to produce a TTI is added once thearticle is cooled. It should also be noted although some applications ofinorganic chromophores require high temperature processes, the methodsdescribed here are not required to have a high temperature processingstep. The processes to create TTI's detailed here are general and theinorganic materials may, in some cases, be deposited on plastics, wood,paper, ceramics or glass without heating. In some cases, some of theinorganic emissive materials may, in some cases, be optionallypassivated and provide for a reference signal with a lifetime that isinvariant upon chemical exposure. Passivation may, in some cases, occurby producing structured inorganic emissive materials wherein a particlehas a protective inorganic shell, as well as other ways. To produce aTTI device from these materials fabricated under the conditions of highheat will require a final over-coating step of a cofactor which may, insome cases, be performed at a later stage. The cofactor may, in somecases, be a quencher or a light harvesting antenna or a material thatbinds to the particle or combinations thereof. In some cases, a cofactormay, in some cases, be applied that quenches the inorganic emissivematerial and may, in some cases, be lost by thermal volatilization ordiffusion into an overcoating material. In this case a thermal eventwill give an increase in the intensity of the inorganic emitter and/orits emissive lifetime. The quencher need not be applied evenly acrossthe areas containing the inorganic emitter. In some cases, only part ofthe inorganic emitter need be treated with the quencher and in this waya reference emissive material is produced in conjunction with thermallyresponsive emissive material. It is also possible to apply variableamounts of quencher in a known pattern with the locations on the productwhere the quencher is applied more sparingly activated (display anincrease in the emission intensity and/or lifetime) by lower degrees ofthermal exposure. Locations on the product wherein the quencher isapplied in a larger quantity will activate at higher temperature timedosages. Comparisons of these effects may, in some cases, yield TTIinformation of interest for a given product.

It is also possible to use cofactors that behave as antennas withinorganic emitters that have been fused to surfaces at hightemperatures. For example, isolated Eu⁺³ ions without coordinatedorganic ligands have very limited absorption, particularly in thevisible region of the electromagnetic spectrum. Europium ions may, insome cases, be embedded into a glass or similar substrate by heatingnanoparticles or heating materials applied from a dispersion of EuCl₃.Application of a cofactor that is capable of absorbing light and bindingto the Eu⁺³ ions may, in some cases, then be used to produce an emissivestate with an appropriate emissive lifetime. The antenna chromophoresare behaving as ligands and other added ligands that either bindstronger to the Eu⁺³ or are in greater abundance may, in some cases, beused to produce a TTI. For example, a pyridine containing chromophoremay, in some cases, be bound to an Eu⁺³ species and in the presence of astronger binding ligand may, in some cases, be displaced with a thermaltreatment. If the displacing ligand, which may, in some cases, includephosphine oxides, 4,4′-bipyridyls, terpyridyls, or 1,10-phenanthrolines,do not produce Eu⁺³ complexes that absorb at the wavelength of theexcitation, then the europium based emissive species will diminish. Theamount of displacing ligand may, in some cases, be varied and there may,in some cases, be an excess of the starting antenna ligand. As withother methods, variations in the matrix, concentration, and otheraspects of the environment may, in some cases, be used to produce athermally activated response that produces the desired TTI.

It is also possible to have an initial state wherein some or all of theEu⁺³ sites are bound with ligands that do not allow for excitation atthe applied wavelengths. Application of an antenna chromophore that may,in some cases, displace these ligands under the desired thermal exposureconditions may, in some cases, then produce a means to produce a TTI.Combinations of ligand concentration, matrix material, spatialpositioning and the like may, in some cases, be used to produce a TTIwith the proper response profile for a given product.

Similar schemes may, in some cases, be anticipated for other metal ions,including terbium (Tb⁺³), erbium (Er⁺³), yttrium (Yb⁺³) and a variety ofother metals including gold, silver, palladium, platinum, manganese,titanium, and ruthenium. Main group elements including tin, lead,bismuth, cadmium, indium and other heavy elements may, in some cases,also be used to create responsive materials capable of producingemission behaviors in response to a thermal exposure to create a TTI.Nanoparticle systems may, in some cases, also be used containing maingroup or transition metal ions with fluoride, oxygen, sulfur, selenium,and telluride.

Some products may, in some cases, be damaged by excessively coldtemperatures and freezing of samples may, in some cases, causeirreversible damage to the product. Products may be unstable uponfreezing and not return to their initial state. In many cases these areproducts involving aqueous solutions or aqueous gels, but the productsmay, in some cases, have many forms. For example, it may be of interestto determine if fish has been frozen prior to selling it in a retailstore. Similarly, freezing will compromise many beverages. Freezing of asolution of gel will often cause phase separation when one of thecomponents crystallizes. Such a process may, in some cases, lead to theassembly or deconstruction of a material displaying a delayed emission.Detecting changes in the emission intensities, absorption and emissionwavelengths, and excited state lifetimes may, in some cases, be used toproduce a TTI that reflects the cold exposure of a product. Gelmaterials may, in some cases, be used to host the components to createthese cold exposure TTIs and these materials have the advantage thatthey may, in some cases, be patterned to create more information.

The analysis of spatial patterns of materials displaying delayedemission may, in some cases, be used to quantify a thermal exposure.Compositions fabricated from phase separated materials may, in somecases, be patterned in ways able to produce a TTI code providing moreinformation than a simple threshold exposure. For example, by creatingpatterns of the components needed to produce a TTI with differentspacing between multiple active elements that must diffuse together toproduce the signal, a gradation of thermal exposures may, in some cases,then be determined yielding more granular data. Materials wherein thepattern requires only short-range diffusion will respond first and onlywith longer thermal exposures will the wider spaced materials achievethe required diffusion. Similar to optical bar codes and QR codes thedelayed emissive signatures created by thermal exposure or cold exposuremay, in some cases, be used to provide information. This sameinformation may, in some cases, also be used in product authenticationand in many cases the patterns collected from delayed emission may, insome cases, be used in conjunction with other optical codes that provideinformation about the product (lot number, date of manufacture, place oforigin, etc.) that may, in some cases, be integrated with theinformation from the TTI. The patterns may, in some cases, be complexand need not be limited to a single delayed emission species as the TTIbut may, in some cases, contain multiple delayed emission species aswell as different mechanisms for the TTI response. Reference emissionsmay, in some cases, also be integrated into the materials that providefor spatial positioning, excited state lifetimes, and intensityinformation. The delayed emission readers that capture information fromthe TTIs may, in some cases, also vary. Readers may, in some cases,range from a fast laser pulse with time resolved lifetimes, to devicesthat use shutters to gate both the excitation and emission collection.Readers may, in some cases, be used that resolve lifetimes andwavelengths and in this case the reader may, in some cases, be a streakcamera. Smart phones and other devices incorporating CMOS imaging chipssuch as digital cameras may, in some cases, also be used to read TTIsvia the rolling shutter effect.

As described above, in some embodiments, a system comprises anexcitation component. In some instances, the excitation componentcomprises a source of electromagnetic radiation. The source ofelectromagnetic radiation may be a source of any type of electromagneticradiation (i.e., electromagnetic radiation of any wavelength). Suitabletypes of electromagnetic radiation that may be emitted by the source ofelectromagnetic radiation include, but are not limited to, ultravioletradiation (e.g., having a wavelength in a range from about 10 nm toabout 380 nm), visible light (e.g., having a wavelength in a range fromabout 380 nm to about 740 nm), near-infrared radiation (e.g., having awavelength in a range from about 700 nm to about 800 nm), and infraredradiation (e.g., having a wavelength in a range from about 740 nm toabout 3 μm).

In some embodiments, the source of electromagnetic radiation isconfigured to emit broadband radiation. In certain instances, the sourceof electromagnetic radiation is configured to emit electromagneticradiation in a wavelength range spanning at least 350 nm, at least 360nm, at least 370 nm, at least 380 nm, at least 390 nm, at least 400 nm,at least 500 nm, at least 1 μm, at least 2 μm, or at least 3 μm. Incertain instances, the source of electromagnetic radiation is configuredto emit electromagnetic radiation in a wavelength range spanning 350 nmto 400 nm, 350 nm to 500 nm, 350 nm to 1 μm, 350 nm to 2 μm, 350 nm to 3μm, 400 nm to 500 nm, 400 nm to 1 μm, 400 nm to 2 μm, 400 nm to 3 μm,500 nm to 1 μm, 500 nm to 2 μm, 500 nm to 3 μm, 1 μm to 2 μm, or 1 μm to3 μm. In some embodiments, the source of electromagnetic radiation isconfigured to emit substantially white light.

In some embodiments, the source of electromagnetic radiation isconfigured to emit electromagnetic radiation in a wavelength rangespanning at least 350 nm, at least 360 nm, at least 370 nm, at least 380nm, at least 390 nm, at least 400 nm, at least 500 nm, at least 600 nm,at least 700 nm, or at least 800 nm. In certain instances, the source ofelectromagnetic radiation is configured to emit electromagneticradiation in a wavelength range of greater than or equal to 350 nm,greater than or equal to 400 nm, greater than or equal to 450 nm,greater than or equal to 500 nm, greater than or equal to 550 nm,greater than or equal to 600 nm, greater than or equal to 650 nm,greater than or equal to 700 nm, or greater than or equal to 750 nm andless than or equal to 800 nm, less than or equal to 750 nm, less than orequal to 700 nm, less than or equal to 650 nm, less than or equal to 600nm, less than or equal to 550 nm, less than or equal to 500 nm, lessthan or equal to 450 nm, or less than or equal to 400 nm. Combinationsof the above referenced ranges are also possible (e.g., greater than orequal to 350 nm and less than or equal to 800 nm). Other ranges are alsopossible.

In some embodiments, the source of electromagnetic radiation isconfigured to emit electromagnetic radiation in relatively narrow rangesof wavelengths. In certain cases, for example, the source ofelectromagnetic radiation is configured to emit electromagneticradiation in a discrete wavelength range that selectively excitesparticular emissive species. In some embodiments, the source ofelectromagnetic radiation is configured to emit electromagneticradiation in a discrete wavelength range spanning 350 nm or less, 300 nmor less, 200 nm or less, 100 nm or less, 90 nm or less, 80 nm or less,70 nm or less, 60 nm or less, 50 nm or less, 40 nm or less, 30 nm orless, 20 nm or less, or 10 nm or less. In some embodiments, the sourceof electromagnetic radiation is configured to emit electromagneticradiation in a discrete wavelength range spanning 10 nm to 20 nm, 10 nmto 40 nm, 10 nm to 50 nm, 10 nm to 60 nm, 10 nm to 80 nm, 10 nm to 100nm, 10 nm to 200 nm, 10 nm to 300 nm, 10 nm to 350 nm, 20 nm to 40 nm,20 nm to 50 nm, 20 nm to 60 nm, 20 nm to 80 nm, 20 nm to 100 nm, 20 nmto 200 nm, 20 nm to 300 nm, 20 nm to 350 nm, 40 nm to 60 nm, 40 nm to 80nm, 40 nm to 100 nm, 40 nm to 200 nm, 40 nm to 300 nm, 40 nm to 350 nm,50 nm to 100 nm, 50 nm to 200 nm, 50 nm to 300 nm, 50 nm to 350 nm, 100nm to 200 nm, 100 nm to 300 nm, or 100 nm to 350 nm.

In some embodiments, the source of electromagnetic radiation isconfigured to emit electromagnetic radiation in a discrete wavelengthrange spanning 500 nm or less, 400 nm or less, 350 nm or less, 300 nm orless, 200 nm or less, 100 nm or less, 90 nm or less, 80 nm or less, 70nm or less, 60 nm or less, 50 nm or less, 40 nm or less, 30 nm or less,20 nm or less, or 200 nm or less. In some embodiments, the source ofelectromagnetic radiation is configured to emit electromagneticradiation in a discrete wavelength range spanning 200 nm to 20 nm, 200nm to 40 nm, 200 nm to 50 nm, 200 nm to 60 nm, 200 nm to 80 nm, 200 nmto 100 nm, 200 nm to 200 nm, 200 nm to 300 nm, 200 nm to 350 nm, 20 nmto 40 nm, 20 nm to 50 nm, 20 nm to 60 nm, 20 nm to 80 nm, 20 nm to 100nm, 20 nm to 200 nm, 20 nm to 300 nm, 20 nm to 350 nm, 40 nm to 60 nm,40 nm to 80 nm, 40 nm to 100 nm, 40 nm to 200 nm, 40 nm to 300 nm, 40 nmto 350 nm, 50 nm to 100 nm, 50 nm to 200 nm, 50 nm to 300 nm, 50 nm to350 nm, 100 nm to 200 nm, 100 nm to 300 nm, or 100 nm to 500 nm.

In some embodiments, the source of electromagnetic radiation isconfigured to emit substantially violet light (e.g., light having a peakwavelength in a range of 400 nm to 450 nm), substantially blue light(e.g., light having a peak wavelength in a range from 450 nm to 490 nm),substantially cyan light (e.g., light having a peak wavelength in arange from 490 nm to 520 nm), substantially green light (e.g., lighthaving a peak wavelength in a range from 520 nm to 560 nm),substantially yellow light (e.g., light having a peak wavelength in arange from 560 nm to 590 nm), substantially orange light (e.g., lighthaving a peak wavelength in a range from 590 nm to 635 nm), and/orsubstantially red light (e.g., light having a peak wavelength in a rangefrom 635 nm to 700 nm). In some embodiments, the source ofelectromagnetic radiation is configured to emit electromagneticradiation in a plurality of relatively narrow ranges of wavelengths. Incertain instances, the source of electromagnetic radiation is configuredto emit electromagnetic radiation in at least 2 discrete ranges, atleast 3 discrete ranges, at least 4 discrete ranges, or at least 5discrete ranges.

In some embodiments, the source of electromagnetic radiation has atleast a first portion of the electromagnetic radiation spectrumcomprising a wavelength of between greater than or equal to 425 nm andless than or equal to 475 nm (e.g., greater than or equal to 425 nm andless than or equal to 450 nm). In some embodiments, a second portion ofthe electromagnetic radiation spectrum produced by the source ofelectromagnetic radiation comprises a wavelength of greater than orequal to 525 nm and less than or equal to 725 nm (e.g., greater than orequal to 600 nm and less than or equal to 725 nm, greater than or equalto 600 nm and less than or equal to 700 nm). In some embodiments, thesource of electromagnetic radiation has at least a first portion of theelectromagnetic radiation spectrum comprising a wavelength of betweengreater than or equal to 425 nm and less than or equal to 525 nm (e.g.,greater than or equal to 425 nm and less than or equal to 525 nm). Insome embodiments, a second portion of the electromagnetic radiationspectrum produced by the source of electromagnetic radiation comprises awavelength of greater than or equal to 525 nm and less than or equal to725 nm. In some embodiments, the source of electromagnetic radiationproduces white light.

In an exemplary set of embodiments, the source of electromagneticradiation is configured to emit substantially white light. For example,the source of electromagnetic radiation emits light having a rangebetween at least 350 nm and less than or equal to 800 nm and has a peakin the range of spanning at least 350 nm, at least 360 nm, at least 370nm, at least 380 nm, at least 390 nm, at least 400 nm, at least 500 nm,at least 600 nm, at least 700 nm, or at least 800 nm. In certaininstances, the source of electromagnetic radiation is configured to emitelectromagnetic radiation in a wavelength range of greater than or equalto 350 nm, greater than or equal to 400 nm, greater than or equal to 450nm, greater than or equal to 500 nm, greater than or equal to 550 nm,greater than or equal to 600 nm, greater than or equal to 650 nm,greater than or equal to 700 nm, or greater than or equal to 750 nm andless than or equal to 800 nm, less than or equal to 750 nm, less than orequal to 700 nm, less than or equal to 650 nm, less than or equal to 600nm, less than or equal to 550 nm, less than or equal to 500 nm, lessthan or equal to 450 nm, or less than or equal to 400 nm.

In some embodiments, the source produces a wavelength of electromagneticradiation that interacts with the emissive species such that theemissive species produces a detectable signal having one or more delayedemissions of greater than or equal to 10 nanoseconds, as describedherein.

The excitation component may comprise one or more sources ofelectromagnetic radiation, and the one or more sources ofelectromagnetic radiation may comprise any suitable source ofelectromagnetic radiation. Examples of suitable sources ofelectromagnetic radiation include, but are not limited to,light-emitting diodes (LEDs), organic light-emitting diodes (OLEDs),flash bulbs, emissive species (e.g., fluorescent dyes, inorganicphosphors), room lights, and electrical discharge sources. In someembodiments, the excitation component comprises a plurality of sourcesof electromagnetic radiation (e.g., a plurality of LEDs, OLEDs, flashbulbs, emissive species, and/or electrical discharge sources). In somecases, two or more sources of electromagnetic radiation are configuredto emit electromagnetic radiation in the same range of wavelengths. Insome instances, each electromagnetic radiation source of the pluralityof electromagnetic radiation sources is configured to emitelectromagnetic radiation in the same range of wavelengths. In somecases, two or more sources of electromagnetic radiation are configuredto emit electromagnetic radiation in different ranges of wavelengths. Insome instances, each electromagnetic radiation source of the pluralityof electromagnetic radiation sources is configured to emitelectromagnetic radiation in different ranges of wavelengths.

In some embodiments, the electromagnetic radiation emitted by anexcitation component is pulsed and/or modulated. Time varying excitationis generally said to be a non-steady-state excitation. In someembodiments, an excitation component is configured to emitelectromagnetic radiation such that at least one characteristic of theelectromagnetic radiation (e.g., intensity, wavelength, polarization) ismodulated over time. In some embodiments, an excitation component isconfigured to emit one or more pulses of electromagnetic radiation. Insome embodiments, the excitation component emits a complex pattern ofpulses and modulated electromagnetic radiation that may be in sequenceor overlapping in time, polarization, spatial position on the article,and/or wavelength. The excitation component may emit one or more pulsesof any duration at any pulse rate. In some embodiments, the excitationcomponent is configured to emit one or more pulses of electromagneticradiation having a duration of 10 milliseconds (ms) or less, 1 ms orless, 100 microseconds (μm) or less, 10 μm or less, 1 μm or less, 100nanoseconds (ns) or less, 10 ns or less, 5 ns or less, 2 ns or less, 1ns or less, 500 picoseconds (ps) or less, 200 ps or less, 100 ps orless, 50 ps or less, 20 ps or less, 10 ps or less, or 1 ps or less. Insome embodiments, the excitation component is configured to emit one ormore pulses of electromagnetic radiation having a duration in a rangefrom 1 ps to 10 ps, 1 ps to 20 ps, 1 ps to 50 ps, 1 ps to 100 ps, 1 psto 200 ps, 1 ps to 500 ps, 1 ps to 1 ns, 1 ps to 2 ns, 1 ps to 5 ns, 1ps to 10 ns, 10 ps to 50 ps, 10 ps to 100 ps, 10 ps to 200 ps, 10 ps to500 ps, 10 ps to 1 ns, 10 ps to 2 ns, 10 ps to 5 ns, 10 ps to 10 ns, 100ps to 500 ps, 100 ps to 1 ns, 100 ps to 2 ns, 100 ps to 5 ns, 100 ps to10 ns, 1 ns to 5 ns, or 1 ns to 10 ns.

In some embodiments, an excitation component is configured to emit oneor more pulses of electromagnetic radiation at a relatively high pulserate (e.g., similar or higher than an image capture rate of an imagesensor). In some cases, an excitation component is configured to emitone or more pulses of electromagnetic radiation within a single cycle ofimage capture by an image sensor (or, in some cases, within multipleimage capture cycles). In some cases, an excitation component isconfigured to produce a modulated intensity of electromagnetic radiationthat varies over a single cycle of image capture by an image sensor (or,in some cases, within multiple image capture cycles). In some cases, anexcitation component is timed with an image capture such that imagescreated from photon emissions at different delay times with regard tothe excitation pulse or modulation are produced.

After emission of the one or more pulses of electromagnetic radiation,any electromagnetic radiation emitted by an emissive species may bemonitored by the image sensor as a function of time.

In some embodiments, the excitation component is configured to emit oneor more pulses of electromagnetic radiation at a pulse rate of at least1 pulse/s, at least 2 pulses/s, at least 5 pulses/s, at least 10pulses/s, at least 15 pulses/s, at least 20 pulses/s, at least 50pulses/s, or at least 100 pulses/s. In some embodiments, the excitationcomponent is configured to emit one or more pulses of electromagneticradiation at a pulse rate in a range from 1 to 5 pulses/s, 1 to 10pulses/s, 1 to 15 pulses/s, 1 to 20 pulses/s, 1 to 50 pulses/s, 1 to 100pulses/s, 5 to 10 pulses/s, 5 to 15 pulses/s, 5 to 20 pulses/s, 5 to 50pulses/s, 5 to 100 pulses/s, 10 to 20 pulses/s, 10 to 50 pulses/s, 10 to100 pulses/s, 20 to 50 pulses/s, 20 to 100 pulses/s, or 50 to 100pulses/s.

In some embodiments, an excitation component comprises a source ofelectromagnetic radiation that is configured to emit pulsed and/ormodulated electromagnetic radiation. In some embodiments, an excitationcomponent comprises a source of electromagnetic radiation that isconfigured to emit a substantially continuous stream of electromagneticradiation.

In some embodiments, an excitation component comprises a componentconfigured to facilitate pulsing and/or modulation of electromagneticradiation emitted by a source of electromagnetic radiation. Thecomponent may be a mechanical and/or electronic. Non-limiting examplesof suitable mechanical and/or electronic components include opticalshutters, rotating elements (e.g., choppers), lasers, moving mirrors,dynamic refractory materials, and other optical modulators. Examples ofsuitable optical shutters include mechanical shutters, light valves(e.g., liquid crystal light modulators), and molecular crystals thatrespond to mechanical and/or thermal stresses and/or to electricalfields, but a person of ordinary skill in the art would understand thatother types of shutters may be used. The frequency or time period of themodulated electromagnetic radiation can, in some cases, be paired withthe response time (frame rate) of the imaging device. The modulationtime period will, in some embodiments, often be faster than the overallframe rate, but may be close to the time between reading of the rows orcolumns of image pixels with the rolling shutter mechanism. In somecases, having the modulation time period close in time to delays betweenreading of the rows or columns will create information when paired witha time dependent emission with a similar time period.

In some embodiments, systems and methods described herein couple thepulse profile (e.g., rate, shape) of electromagnetic radiation emittedby an excitation component with the lifetime of an emissive species andthe image capture rate of an image sensor. Advantageously, the couplingof these components enables, in some embodiments, determination of thecharacteristic of a particular emissive species (e.g., emissionlifetime), which may in turn provide information about a characteristicof an associated article. By way of example, the measured emissionlifetime of a particular emissive species may provide information aboutthe environment (e.g., presence of certain molecules, temperature, pH)in which the emissive species is located.

As an illustrative embodiment, FIG. 4 shows a single image of a pulsingLED captured by a smartphone using a rolling shutter method and a topcaption indicating whether the LED was on or off. In FIG. 4 , the pulserate of the LED is faster than the total image capture rate of thesmartphone, and a banding structure is visible. In particular, some rowsof the image capture the LED in its “on” state, while subsequent rowscapture the LED in its “off” state.

To further illustrate, FIG. 5 shows an image of a pulsing UV-LEDexciting a fast emissive species (left), as captured by a smartphoneusing a rolling shutter method. The image of the fast emissive speciesis accompanied by a plot of pixel intensity. FIG. 5 also shows an imageof a pulsing UV-LED exciting a delayed emissive species (right), ascaptured by a smartphone using a rolling shutter method. The image ofthe delayed emissive species is also accompanied by a plot of pixelintensity. From FIG. 5 , it may be seen that the image of the delayedemissive species contains bands that appear “fuzzy.” This “fuzziness”may be due at least in part to delayed emission occurring after theUV-LED was turned off.

According to some embodiments, a component of a system (e.g., an imagesensor) detects at least a portion of a detectable emission (e.g., adetectable non-steady-state emission) produced by an emissive speciesduring an emission time period (also referred to as an emissionlifetime). A person of ordinary skill in the art would understand thatan emissive species may produce a detectable emission throughphosphorescence, fluorescence, and/or reflection/scattering (e.g.,reflection of ambient electromagnetic radiation and/or electromagneticradiation emitted by an excitation component). A person of ordinaryskill in the art would also understand that an emission time period oremission lifetime generally refers to the time during which an emissivespecies emits electromagnetic radiation after any excitation radiationhas been removed (e.g., after a pulse of electromagnetic radiation hasbeen emitted by an excitation component).

An emissive species generally has an intrinsic emission lifetime, alsoreferred to as an excited state lifetime, that may be determined byintrinsic radiative and non-radiative decay rates, as represented by thefollowing formula:k _(radiative) +k _(non-radiative)=1/intrinsic emission lifetimeHowever, the emission lifetime is generally dependent on the context andvalues may change with different solvents or solid forms. For example,the observed emission lifetime of a species may differ from theintrinsic emission lifetime. For example, when other quenching processesare present, the observed emission lifetime may be calculated accordingto the following formula:k _(radiative) +k _(non-radiative) +k _(quenching)=1/observed emissionlifetimeThus, the observed emission lifetime would be shorter than the intrinsicemission lifetime. As discussed below, numerous factors (e.g., presenceof other molecules, temperature, radiation exposure) may affect theemission lifetime of an emissive species such that an observed emissionlifetime is different than (e.g., greater than, less than) the intrinsicemission lifetime of the emissive species. The radiative rate(k_(radiative)) contains all of the different emission processes and maybe measured as the weighted average of processes that have differentrates of emission. The measured emission rate may, in some cases, varywithin a measurement of a species. For example, in TADFdelayed-fluorescence with excitation there may be prompt-fluorescencefollowed by a transition to the TADF process wherein the excited statedisplays the singlet-triplet equilibrium.

In systems and methods described herein, an emissive species has anintrinsic emission lifetime of any suitable length. In certain cases, anemissive species has a relatively long intrinsic emission lifetime. Insome embodiments, an emissive species has an intrinsic emission lifetimeof at least 1 nanosecond (ns), at least 5 ns, at least 10 ns, at least20 ns, at least 50 ns, at least 100 ns, at least 200 ns, at least 500ns, at least 1 μs, at least 10 μs, at least 50 μs, at least 100 μs, atleast 500 μs, at least 1 ms, at least 5 ms, at least 10 ms, at least 50ms, at least 100 ms, at least 500 ms, at least 1 s, at least 2 s, atleast 3 s, at least 4 s, at least 5 s, at least 6 s, at least 7 s, atleast 8 s, at least 9 s, or at least 10 s. In some embodiments, anemissive species has an intrinsic emission lifetime in a range from 1 nsto 10 ns, 1 ns to 20 ns, 1 ns to 50 ns, 1 ns to 100 ns, 1 ns to 500 ns,1 ns to 1 μs, 1 ns to 5 μs, 1 ns to 10 μs, 1 ns to 50 μs, 1 ns to 100μs, 1 ns to 500 μs, 1 ns to 1 ms, 1 ns to 5 ms, 1 ns to 10 ms, 1 ns to50 ms, 1 ns to 100 ms, 1 ns to 500 ms, 1 ns to 1 s, 1 ns to 5 s, 1 ns to10 s, 10 ns to 20 ns, 10 ns to 50 ns, 10 ns to 100 ns, 10 ns to 500 ns,10 ns to 1 μs, 10 ns to 5 μs, 10 ns to 10 μs, 10 ns to 50 μs, 10 ns to100 μs, 10 ns to 500 μs, 10 ns to 1 ms, 10 ns to 5 ms, 10 ns to 10 ms,10 ns to 50 ms, 10 ns to 100 ms, 10 ns to 500 ms, 10 ns to 1 s, 10 ns to5 s, 10 ns to 10 s, 50 ns to 100 ns, 50 ns to 500 ns, 50 ns to 1 μs, 50ns to 5 μs, 50 ns to 10 μs, 50 ns to 50 μs, 50 ns to 100 μs, 50 ns to500 μs, 50 ns to 1 ms, 50 ns to 5 ms, 50 ns to 10 ms, 50 ns to 50 ms, 50ns to 100 ms, 50 ns to 500 ms, 50 ns to 1 s, 50 ns to 5 s, 50 ns to 10s, 100 ns to 500 ns, 100 ns to 1 μs, 100 ns to 5 μs, 100 ns to 10 μs,100 ns to 50 μs, 100 ns to 100 μs, 100 ns to 500 μs, 100 ns to 1 ms, 100ns to 5 ms, 100 ns to 10 ms, 100 ns to 50 ms, 100 ns to 100 ms, 100 nsto 500 ms, 100 ns to 1 s, 100 ns to 5 s, or 100 ns to 10 s. Other rangesare also possible.

In some embodiments, an emissive species has an observed emissionlifetime (e.g., a measured emission time period) of any suitable length.In certain cases, an emissive species has a relatively long observedemission lifetime relative to typical fluorescent dyes that are presentin many articles or in natural systems (e.g., at least 10 ns). Arelatively long observed emission lifetime may, in some cases, allow asingle image to show emission from an emissive species when anexcitation source is turned off. In so doing, the slower emissions maybe observed once the faster emissions are absent. In certain instances,an emissive species has an observed emission lifetime that may bemeasured using consumer-level electronics (e.g., a smartphone, a digitalcamera). In some embodiments, an emissive species has an observedemission lifetime (e.g., a measured emission time period) of at least 1nanosecond (ns), at least 5 ns, at least 10 ns, at least 20 ns, at least50 ns, at least 100 ns, at least 200 ns, at least 500 ns, at least 1 μs,at least 10 μs, at least 50 μs, at least 100 μs, at least 500 μs, atleast 1 ms, at least 5 ms, at least 10 ms, at least 50 ms, at least 100ms, at least 500 ms, at least 1 s, at least 2 s, at least 5 s, or atleast 10 s.

In some embodiments, an emissive species has an observed emissionlifetime (e.g., a measured emission time period) of 10 s or less, 5 s orless, 2 s or less, 1 s or less, 500 ms or less, 100 ms or less, 50 ms orless, 10 ms or less, 5 ms or less, 1 ms or less, 500 μs or less, 100 μsor less, 50 μs or less, 10 μs or less, 1 μs or less, 500 ns or less, 200ns or less, 100 ns or less, 50 ns or less, 10 ns or less, 5 ns or less,or 1 ns or less. In certain cases, an emissive species having a shorterobserved emission lifetime (e.g., 0.1 second or less) may provide higheraverage signals than an emissive species having a longer observedemission lifetime because the electromagnetic radiation emission isspread over a shorter period. In addition, an emissive species having ashorter observed emission lifetime (e.g., 0.1 second or less) mayadvantageously allow collection of lifetime images to occur at a fasterrate than an emissive species having a longer observed emissionlifetime.

In some embodiments, an emissive species has an observed emissionlifetime (e.g., a measured emission time period) in a range from 1 ns to10 ns, 1 ns to 20 ns, 1 ns to 50 ns, 1 ns to 100 ns, 1 ns to 500 ns, 1ns to 1 μs, 1 ns to 5 μs, 1 ns to 10 μs, 1 ns to 50 μs, 1 ns to 100 μs,1 ns to 500 μs, 1 ns to 1 ms, 1 ns to 5 ms, 1 ns to 10 ms, 1 ns to 50ms, 1 ns to 100 ms, 1 ns to 500 ms, 1 ns to 1 s, 1 ns to 5 s, 1 ns to 10s, 10 ns to 20 ns, 10 ns to 50 ns, 10 ns to 100 ns, 10 ns to 500 ns, 10ns to 1 μs, 10 ns to 5 μs, 10 ns to 10 μs, 10 ns to 50 μs, 10 ns to 100μs, 10 ns to 500 μs, 10 ns to 1 ms, 10 ns to 5 ms, 10 ns to 10 ms, 10 nsto 50 ms, 10 ns to 100 ms, 10 ns to 500 ms, 10 ns to 1 s, 10 ns to 5 s,10 ns to 10 s, 50 ns to 100 ns, 50 ns to 500 ns, 50 ns to 1 μs, 50 ns to5 μs, 50 ns to 10 μs, 50 ns to 50 μs, 50 ns to 100 μs, 50 ns to 500 μs,50 ns to 1 ms, 50 ns to 5 ms, 50 ns to 10 ms, 50 ns to 50 ms, 50 ns to100 ms, 50 ns to 500 ms, 50 ns to 1 s, 50 ns to 5 s, 50 ns to 10 s, 100ns to 500 ns, 100 ns to 1 μs, 100 ns to 5 μs, 100 ns to 10 μs, 100 ns to50 μs, 100 ns to 100 μs, 100 ns to 500 μs, 100 ns to 1 ms, 100 ns to 5ms, 100 ns to 10 ms, 100 ns to 50 ms, 100 ns to 100 ms, 100 ns to 500ms, 100 ns to 1 s, 100 ns to 5 s, 100 ns to 10 s, 1 μs to 5 μs, 1 μs to10 μs, 1 μs to 50 μs, 1 μs to 100 μs, 1 μs to 500 μs, 1 μs to 1 ms, 1 μsto 5 ms, 1 μs to 10 ms, 1 μs to 50 ms, 1 μs to 100 ms, 1 μs to 500 ms, 1μs to 1 s, 1 μs to 5 s, 1 μs to 10 s, 10 μs to 50 μs, 10 μs to 100 μs,10 μs to 500 μs, 10 μs to 1 ms, 10 μs to 5 ms, 10 μs to 10 ms, 10 μs to50 ms, 10 μs to 100 ms, 10 μs to 500 ms, 10 μs to 1 s, 10 μs to 5 s, 10μs to 10 s, 100 μs to 500 μs, 100 μs to 1 ms, 100 μs to 5 ms, 100 μs to10 ms, 100 μs to 50 ms, 100 μs to 100 ms, 100 μs to 500 ms, 100 μs to 1s, 100 μs to 5 s, 100 μs to 10 s, 1 ms to 5 ms, 1 ms to 10 ms, 1 ms to50 ms, 1 ms to 100 ms, 1 ms to 500 ms, 1 ms to 1 s, 1 ms to 5 s, 1 ms to10 s, 10 ms to 50 ms, 10 ms to 100 ms, 10 ms to 500 ms, 10 ms to 1 s, 10ms to 5 s, 10 ms to 10 s, 100 ms to 500 ms, 100 ms to 1 s, 100 ms to 5s, 100 ms to 10 s, 1 s to 5 s, or 1 s to 10 s.

An emissive species may be selected to emit any suitable type ofelectromagnetic radiation (i.e., electromagnetic radiation of anywavelength). Suitable types of electromagnetic radiation that may beemitted by an emissive species include, but are not limited to,ultraviolet radiation (e.g., having a wavelength in a range from about10 nm to about 380 nm), visible light (e.g., having a wavelength in arange from about 380 nm to about 740 nm), near-infrared radiation (e.g.,having a wavelength in a range from about 700 nm to about 800 nm), andinfrared radiation (e.g., having a wavelength in a range from about 740nm to about 3 μm). In some embodiments, an emissive species isconfigured to emit electromagnetic radiation having a wavelength in arange from 200 nm to 380 nm, 200 nm to 400 nm, 200 nm to 600 nm, 200 nmto 740 nm, 200 nm to 800 nm, 200 nm to 1 μm, 200 nm to 2 μm, 200 nm to 3μm, 380 nm to 600 nm, 380 nm to 740 nm, 380 nm to 800 nm, 380 nm to 1μm, 380 nm to 2 μm, 380 nm to 3 μm, 400 nm to 600 nm, 400 nm to 740 nm,400 nm to 800 nm, 400 nm to 1 μm, 400 nm to 2 μm, 400 nm to 3 μm, 600 nmto 740 nm, 600 nm to 800 nm, 600 nm to 1 μm, 600 nm to 2 μm, 600 nm to 3μm, 700 nm to 800 nm, 740 nm to 1 μm, 740 nm to 2 μm, 740 nm to 3 μm,800 nm to 1 μm, 800 nm to 2 μm, 800 nm to 3 μm, 1 μm to 2 μm, or 1 μm to3 μm.

In some embodiments, an emissive species is configured to emit visiblelight. In certain cases, an emissive species is configured to emitsubstantially violet light (e.g., light having a peak wavelength in arange of 400 nm to 450 nm), substantially blue light (e.g., light havinga peak wavelength in a range from 450 nm to 490 nm), substantially cyanlight (e.g., light having a peak wavelength in a range from 490 nm to520 nm), substantially green light (e.g., light having a peak wavelengthin a range from 520 nm to 560 nm), substantially yellow light (e.g.,light having a peak wavelength in a range from 560 nm to 590 nm),substantially orange light (e.g., light having a peak wavelength in arange from 590 nm to 635 nm), and/or substantially red light (e.g.,light having a peak wavelength in a range from 635 nm to 700 nm). Incertain instances, an emissive species is configured to emitelectromagnetic radiation that is detectable by consumer-levelelectronics (e.g., a smartphone, a digital camera).

In some cases, an emission profile (i.e., a plot of intensity ofelectromagnetic radiation emitted by an emissive species as a functionof time) of an emissive species may be fit to one or more functions(e.g., exponential functions). Multiple lifetimes can result fromdifferent environments around an emissive species and/or have multipleradiative rates. These environments can change with exposure tochemicals, heat, mechanical stress, moisture, cooling, gases, light, andionizing radiation. In certain instances, when an excitation componentemits electromagnetic radiation of oscillating intensity at a fixed orvarying frequency, emission from an emissive species absorbing thatelectromagnetic radiation may exhibit variations resulting from thecomplex excitation profile. In an illustrative, non-limiting example, ifelectromagnetic radiation emitted by an excitation component has asinusoidal profile at a frequency close to the emission lifetime of theemissive species, the resulting electromagnetic radiation emitted by theemissive species (i.e., the species excited by the excitation radiation)will generally have an oscillating intensity that is at the samefrequency, but phase-shifted from the excitation radiation. That is, insome cases, the oscillating intensity of photons emitted by an emissivespecies may be delayed from the oscillating intensity of photons emittedby an excitation component. In some instances, there may be distortionof the intensity of the emitted radiation from the pure sine waveform ofthe exciting radiation.

In some cases, waveform and delay information from an emission profilemay be used to calculate or estimate the emission lifetime of anemissive species. According to some embodiments, an emissive species maybe exposed to a number of different excitation frequencies, anddifferent emission responses may be detected. In some cases, the use ofa standard emitter that has a known and invariant emission lifetime willbe used to determine or estimate an absolute or relative lifetime of anemissive species. In some cases, an excitation component may emitelectromagnetic radiation having complex waveforms, and an emissivespecies absorbing the electromagnetic radiation may produce emissionshaving complex modulations in intensity.

In some embodiments, the emission time period (e.g., observed emissionlifetime) of an emissive species may vary based on environmentalconditions, including but not limited to binding or proximity to othermolecules (e.g., oxygen, water, carbon dioxide, carbon monoxide,quenching molecules), physical alteration, temperature, pH, andradiation exposure. As an illustrative example, FIG. 6 shows opticalmicrographs of a thin film comprising two emissive species exposed todifferent temperatures during image acquisition using rolling shutter.In particular, FIG. 6 shows an image of a thin film at 7° C., underrefrigeration (left), at room temperature (center), and at 54° C., underheating (right). As the temperature increases, the amount of emissionattributable to the emissive species during the “off” state of the LEDdecreases. Without wishing to be bound by a particular theory, this maybe due to the lifetime of the emissive species decreasing as a result ofadditional deactivation pathways.

In some embodiments, a quenching molecule or material is added to theenvironment of an emissive species. A quencher molecule or material mayact as a dynamic and/or static quencher. In certain cases, the quenchingmolecule or material forms a static complex with the emissive species bybinding to the emissive species or being persistently proximate to theemissive species. In some instances, binding or persistent proximity ofa quenching molecule or material to an emissive species changes at leastone characteristic (e.g., wavelength, intensity, emission lifetime) ofelectromagnetic radiation emitted by the emissive species. In someinstances, binding or persistent proximity of a quenching molecule ormaterial to an emissive species quenches emission from the emissivespecies, such that no emission from the emissive species is detected.

In some embodiments, a quenching molecule or material dynamicallyinteracts with an emissive species. In some such embodiments, dynamicinteraction between a quenching molecule or material and an emissivespecies may be controlled by diffusion or other motion. This extraquenching rate of deactivation (k_(Q)) can reduce the observed emissionlifetime the emitting species. In some cases, dynamic interactionbetween a quenching molecule or material and an emissive species changesat least one characteristic (e.g., wavelength, intensity, emissionlifetime, or polarization) of electromagnetic radiation emitted by theemissive species. In some instances, dynamic interaction between aquenching molecule or material and an emissive species quenches emissionfrom the emissive species, such that no emission from the emissivespecies is detected. This may be referred to as saturated dynamicquenching as it requires all of the quenching interactions to happen atfaster times than the lifetime of the emissive species. In anillustrative, non-limiting example, oxygen is present in an environmentsurrounding an emissive species but is not bound to the emissivespecies. Through diffusion, an oxygen molecule may become sufficientlyproximate to an emissive species to quench emission of the emissivespecies (e.g., the distance between the oxygen molecule and the emissivespecies may be small enough that electron or energy transfer can occur).The likelihood that an oxygen molecule will, through diffusion, becomesufficiently proximate to an emissive species to quench emission of theemissive species may depend on factors such as oxygen concentration inthe environment and temperature. For example, a higher oxygenconcentration and/or higher temperature may increase the likelihood thatan oxygen molecule would quench an emissive species. In some cases,therefore, an observed emission lifetime of an emissive species mayprovide information about oxygen concentration and/or temperature. Incertain instances, for example, an emissive species exposed to theinterior of a package may be used to determine oxygen content within thepackage without opening the package. In other cases, a package orcapsule can contain a gas or molecule that quenches or preventsquenching of an emissive molecule. Opening the package or capsule, orcompromises in their containment, may be detected through changes in thelifetime and intensity of emissive species.

A non-limiting example of a suitable quenching molecule is a moleculecomprising an amine. Amines may act as dynamic or static quenchers. Insome cases, amines may react as Lewis or Bronsted bases to create staticcomplexes that change the color and/or intensity of an emissive species.In some cases, amines engage in electron transfer processes that giverise to a dynamic quenching process that may reduce emission lifetime.In certain cases, amines can react with other species to create newdynamic quenchers. As one example, an amine may deprotonate a moleculeto make it more electron rich and capable of dynamically quenching anemissive species through diffusion and electron transfer process. Aminesare indicators of food spoilage and can allow for the detection of thequality of food without opening the packaging. In some cases, an aminemay be a primary diffusive quencher that may be modified by binding tocarbon dioxide to make a carbamic acid, which may alter its quenchingcharacteristics. In some embodiments, a system comprising a dynamicquencher that may be modified by binding to carbon dioxide may be usedto measure carbon dioxide. Such a system or method may be useful in manybiological and packaging contexts.

In some cases, an emissive species may be characterized by an emissionquantum yield. A person of ordinary skill in the art would understandthe emission quantum yield to refer to the ratio of the number ofphotons absorbed by an emissive species to the number of photons emittedby the emissive species. This ratio generally depends on the relativerates of the various deactivation processes. As one example, if theemissive process for an emissive species is fast relative to thenon-emissive processes, the emission quantum yield will be relativelyhigh. In some cases, emission quantum yield may be affected by one ormore intrinsic properties of an emissive species. In some cases,emission quantum yield may be affected by one or more extrinsicproperties (e.g., properties related to a matrix, a solvent, and/or areactive molecule). In certain instances, a quenching molecule ormaterial may completely quench an emissive species, which generallymeans that the emission quantum yield of the emissive species is belowdetection limits.

In some embodiments, at least one characteristic (e.g., emission quantumyield, emission lifetime, intensive, wavelength, polarization) of anemissive species changes as a function of its environment. As anillustrative, non-limiting example, an emissive species may have ahigher emission quantum yield in a hydrophobic environment than in anaqueous environment. Without wishing to be bound by a particular theory,this effect may be related to changes in the solvation of the excitedstate of the emissive species, which may have a different chargedistribution than the ground state. In other cases, water bound toluminescent metal ions or far red emitting dyes can absorb energythrough vibrational states and quench luminescence. In some cases, heavywater (D₂O) may be used to prevent these processes. As another example,aggregation of certain emissive species may increase emission intensityand/or change observed emission lifetime. As yet another example,binding of certain molecules to an emissive species may affect theobserved emission lifetime of the emissive species. For example, a gammacyclodextrin molecular complex may exhibit a particular observedemission lifetime when a single chromophore is bound in its cavity butmay exhibit a different observed emission lifetime when a secondarymolecule binds in the cavity.

An emissive species may have any suitable structure. In someembodiments, the emissive species is a chemical and/or biologicalspecies. In some cases, the emissive species is a fluorophore, aphosphor, an inorganic solid, a salt, or a thermally activated delayedfluorescence (TADF) molecule or molecular complex.

In some embodiments, an emissive species is a TADF molecule or molecularcomplex. A TADF molecule or molecular complex generally refers to one ormore molecules configured to have low spin (i.e., singlet) and high spin(i.e., triplet) states that are sufficiently close in energy that theyundergo dynamic equilibration at room temperature. In some cases, thisdynamic equilibration process involves spin orbit coupling. In somecases, this dynamic equilibration process results in a much slower rateof emission than expected for a singlet state at least in part becausethe triplet state acts as a holding reservoir for excited electrons. Insome instances, a photon may be absorbed by a TADF molecule or molecularcomplex and may initially create a singlet state having a high rate ofemission. The singlet state may be in rapid equilibrium with alower-energy triplet state having a low rate of emission. When themolecule thermally reverts to the singlet state, there is a chance forthe molecule to emit a photon before it converts back to thelower-energy triplet state. As a result, electromagnetic radiation mayleak out of the minority singlet state through fluorescence, but therate of emission is much slower than expected for a singlet state.

In some embodiments, a TADF molecule has a structure that comprises anelectron-rich region and an electron-deficient region. Examples of asuitable electron-rich region include, but are not limited to, aminegroups. Examples of a suitable electron-deficient region include, butare not limited to, imine groups and nitrile groups. In the groundstate, the highest occupied molecular orbital (HOMO) may be localized onthe electron-rich region, and the lowest unoccupied molecular orbital(LUMO) may be localized on the electron-deficient region. To createefficient emission, the half-filled orbitals in the excited state havefinite overlap. In some embodiments, the TADF molecule is in a twistednonplanar state. In some embodiments, the TADF molecule is arranged suchthat the electron-rich and electron-deficient regions are in a co-facialarrangement (i.e., the π-electron systems of the electron-rich andelectron-deficient regions interact in a face-to-face arrangement).Non-limiting examples of TADF molecules are illustrated in the followingstructures.

Non-limiting examples of materials displaying TADF behavior that havesuitable absorption bands to allow for excitation by the light source ofa smartphone are described below. The absorption bands of such materialscan be shifted by the addition of different substituents for optimaloverlap of their absorbance bands with the light intensity profileproduced by smartphone light sources. Systematic changes in structurecan shift the absorptions to longer wavelengths either by raising theHOMO energy, by lowering the LUMO energy, or both.

TADF materials may also be produced be the association of dissimilarmaterials. For example, an electron donating material with a high energyHOMO can be complexed with an electron accepting material that has a lowenergy LUMO. In these types of materials, without wishing to be bound bytheory, the donor and acceptor molecules interact such that theirπ-orbitals mix and a ground state charge-transfer interaction isobserved. The inter-material interaction may be greatly enhanced in theexcited state when an exciplex excited state is produced. The fact thatthe HOMO and LUMO orbitals largely reside on the donor and acceptormaterials, respectively, may result in some exciplex materialsdisplaying TADF behavior. The fact that there are two separate materialsinvolved in the production of these exciplexes, it is possible to createa number of pairwise combinations to create a diversity of exciplexstructures. The exciplex structures may form, in some cases, by thediffusion of molecules to each other and may be useful for creating TTIsdescribed above. The emission efficiency and the lifetimes of theexcited state exciplex structures will vary with environment and thepairs of materials. Additionally, the ability to produce the groundstate charge transfer complex as well as the exciplex will vary based onthe environment. Creating combinations capable of being excited tocreate TADF active exciplexes will involve selecting pairs of donors andacceptors.

Suitable non-limiting examples of acceptor molecules that can be used toproduce compositions with suitable donor molecules to produce TADFbehavior are described below. X substituents can be chosen to produceLUMO states that can be paired with a selected donor material.Additionally, the X substituents may be used to control the structure ofthe exciplex either by restricting the geometries for interacting withthe donor through interactions with the matrix. The X substituents maybe varied independently and the Ar groups indicate an aromatic fragmentthat has functionality that supports the desired properties. Thearomatic group could be a heterocycle or a substituted hydrocarbon.

Non-limiting examples of suitable donor molecules that can be used toproduce TADF behavior in exciplexes with suitable acceptor molecules aredescribed below. The Ar (aromatic) groups may, in some embodiments,include heterocycles. The Ar groups may be, in some embodiments,substituted with groups that promote the TADF behavior by changing theHOMO energies and/or through promoting/directing particular structuralarrangements.

The structures described herein are only intended to be representativeand there are many other possible acceptor and donor molecules that canbe paired to produce TADF in particular contexts/environments. Theinventors of the instant application have recognized that choosingparticular donor and acceptor combinations that may be excited by thelight sources of smartphones (or other consumer electronic devices) maybe approached by consideration of the fact that the π-electron systemsmay be capable of orbital overlap. For example, if the steric bulk ofthe substituents prevent geometries that allow for these interactions,the ability to produce an exciplex may be compromised. Additionally, therelative energy levels of the donor and acceptor molecules need to havethe proper levels to create absorption features that overlap with theoutput of the light sources of the smartphone. To a first approximation,suitable pairs may include those that have a difference in the energy ofthe donor's HOMO and the acceptor's LUMO of approximately 2.75 eV orless. Photons at 450 nm, which is close to the peak photon output ofmany smartphone light sources, generally have an energy of about 2.75 eV(although other energies are also possible). It is possible that theHOMO and LUMO be separated slightly more than 2.75 eV, in someembodiments, for example because of the intrinsic bandwidth of theabsorptions will still allow for finite absorption at 450 nm. It shouldalso be noted that the HOMO and LUMO states of the respective groundstate molecules are generally only an approximation. Charge transferground state complexes typically shift the energy levels with theabsorption involving a change in the electronic levels of theconstituents. The complexities of the environment may also change theenergy levels of the absorptions as well as those of the emissions. Theindividual donor and acceptor materials may also be independentlyemissive and display prompt-fluorescence that can produce anon-steady-state photon emission event.

In some embodiments, non-limiting examples of the TADF materialsdescribed herein are low molar mass molecules. The TADF effect ishowever not limited to small molecules. The active TADF components maybe, for example, pendant groups on polymers, or be integrated directlyinto a polymer backbone. They may be part of an organized or amorphoussolid. They may be constituents of a covalent crystalline or amorphousframework material, which may or may not have porosity. They may beguests in a receptor. For example, a cyclodextrin molecule may host botha donor and acceptor chromophore in its cavity to promote an TADFexciplex. Alternatively, interactions with a receptor, or a matrix, maybe used to enhance or reduce TADF behavior of a material by promotingconformations, by presenting a dipolar potential, by the proximateplacement of a material capable of quenching the excited state, orpreventing quenching by effectively insulating the molecule from itssurroundings. The TADF materials also need not be purely organic innature and may have many other elements including but not limited toboron, silicon, phosphorous, selenium, as well as other main groupelements. Organometallic, metallo-organic, or purely inorganic materialsmay also present as active or structural components in a TADFcomposition.

In some embodiments, an emissive species comprises a TADF molecularcomplex formed from two or more molecules. In some cases, a TADFmolecular complex comprises an exciplex. An exciplex may be formed bytwo or more molecules in which the π-electron systems of the moleculeshave some degree of co-facial arrangement. Advantageously, forming TADFexciplexes through combinations of molecules (e.g., pairwisecombinations of molecules) can result in a wide variety of emissionlifetimes, emission wavelengths, and responsiveness to environmentalfactors. In exciplexes, the emission efficiency often depends on thedynamics of the component molecules relative to each other. For at leastthis reason, the rigidity of the medium and/or the presence of othermolecules may substantially affect emission rates and/or quantum yields.

The TADF materials may be, in some cases, attached to biologicalspecies, or immobilized on particles, and/or bound to surfaces toproduce a desired signal in an assay.

In some cases, a TADF exciplex may have a substantially longerwavelength and/or a substantially longer emission lifetime than thecomponent molecules. In certain instances, for example, each componentmolecule may be intrinsically fluorescent with a relatively shortemission lifetime (e.g., on the order of nanoseconds). Once the TADFexciplex is formed, the TADF exciplex may have a longer emissionlifetime (e.g., on the order of microseconds). In some cases, forming aTADF exciplex advantageously increases the emission lifetime by hundredsto thousands of times.

In some cases, the fact that TADF exciplexes are formed by at least twoseparate molecules may allow for the molecules to be initially separatedby a certain distance and then allowed to interact and form a TADFexciplex by diffusion. Thus, a thermal dosimeter may be developed thatimages materials based the lifetime and wavelength of their emissions.In some cases, TADF exciplex formation may be induced by physicalprocesses (e.g., breaking capsules) and/or changes in viscosity or otherphysical characteristics.

In some embodiments, intermolecular TADF exciplexes are produced inresponse to biomolecular or molecular associations of the localizationof components at a particular location. In some such embodiments, theexciplex is promoted by a co-localization of the two components, whichcan be designed into an assay.

Additional non-limiting examples of pairs of molecules that display TADFbehavior are shown below. In these illustrative examples, the moleculeswith amines are the electron-rich element and the molecules with iminesare the electron-deficient element.

One of ordinary skill in the art would understand that modifying thesubstituents and scaffolds of TADF molecules or molecular complexes canchange the lifetimes and wavelengths of any emissions. In someembodiments, a TADF molecule or molecular complex has an intrinsicemission lifetime of at least 100 ns, at least 1 μs, at least 10 μs, atleast 50 μs, at least 100 μs, at least 500 μs, or at least 1 ms. In someembodiments, a TADF molecule or molecular complex has an intrinsicemission lifetime in a range from 1 μs to 5 μs, 1 μs to 10 μs, 1 μs to50 μs, 1 μs to 100 μs, 1 μs to 500 μs, 1 μs to 1 ms, 10 μs to 50 μs, 10μs to 100 μs, 10 μs to 500 μs, 10 μs to 1 ms, 100 μs to 500 μs, 100 μsto 1 ms, or 500 μs to 1 ms.

In some embodiments, a TADF molecule or molecular complex has anobserved emission lifetime (e.g., a measured emission time period) of atleast 1 μs, at least 10 μs, at least 50 μs, at least 100 μs, at least500 μs, or at least 1 ms. In some embodiments, a TADF molecule ormolecular complex has an observed emission lifetime (e.g., a measuredemission time period) in a range from 1 μs to 5 μs, 1 μs to 10 μs, 1 μsto 50 μs, 1 μs to 100 μs, 1 μs to 500 μs, 1 μs to 1 ms, 10 μs to 50 μs,10 μs to 100 μs, 10 μs to 500 μs, 10 μs to 1 ms, 100 μs to 500 μs, 100μs to 1 ms, or 500 μs to 1 ms.

In some embodiments, a TADF molecule or molecular complex has arelatively high emission quantum yield. In some embodiments, a TADFmolecule or molecular complex has an emission quantum yield of at least0.3, at least 0.4, at least 0.5, at least 0.6, at least 0.7, at least0.8, at least 0.9, or about 0.95. In some embodiments, a TADF molecularor molecular complex has an emission quantum yield in a range from 0.8to 0.9, 0.8 to 0.95, 0.8 to 0.95, 0.8 to 0.95, 0.9 to 0.95.

In some embodiments, an emissive species is substantiallyphosphorescent. In some embodiments, a phosphorescent emissive speciescomprises a heavy atom. In some embodiments, a phosphorescent emissivespecies comprises an organometallic compound.

In some embodiments, an emissive species comprises a heavy atom.Examples of suitable main-group heavy atoms include, but are not limitedto, chlorine, bromine, iodine, sulfur, selenium, tellurium, phosphorus,silicon, and tin. Without wishing to be bound by a particular theory, aheavy atom may convert primary singlet states produced by absorption ofa photon to a triplet state and/or increase the rate of emission suchthat emission lifetimes are in an optimally detectable range. In someembodiments, the heavy atom may be associated with an organic scaffold.

In some embodiments, an emissive species comprises an organometallic ormetallo-organic compound. An organometallic compound generally has ametal ion bound covalently to one or more ligands. In some cases, anorganometallic compound comprises one or more metal-carbon bonds.Non-limiting examples of suitable metals include gold, silver, platinum,iridium, rhenium, ruthenium, and osmium. Non-limiting examples ofsuitable ligands include alkynyl, aryl, heteroaryl, carbonyl, pyridyl,bipyridyl, terpyridyl, porphyrin, thiols, and phthalocyanine groups.Examples of suitable organometallic compounds include, but are notlimited to, rhenium carbonyl bipyridyl compounds, platinum acetylidecompounds, ruthenium bipyridyl compounds, ruthenium terpyridylcompounds, platinum porphyrin compounds, and platinum phthalocyaninecompounds. In some cases, an organometallic compound may be used foroxygen sensing. In some embodiments, for example, platinum porphyrinand/or platinum phthalocyanine compounds may be used for oxygen sensing.

In some embodiments, an emissive species comprises bismuth. A person ofordinary skill in the art would recognize bismuth as a nontoxic heavymetal that is considered a post-transition-metal element. In someembodiments, bismuth forms a phosphorescent compound with one or moreligands (e.g., pyridyl ligands). In other cases, bismuth formsphosphorescent materials of a purely inorganic nature. In certain cases,bismuth forms a biologically friendly salt. In some cases, thebiologically friendly salt may be formulated with dyes.

In some embodiments, an emissive species comprises a lanthanide and/oractinide. Lanthanide and/or actinides generally have highly contractedelectronic states and often produce atomic-like emission profiles withnarrow emission lines. In some embodiments, a lanthanide and/or actinideforms a complex with a ligand (e.g., an organic ligand). In some cases,the ligands may be used to provide different electromagnetic radiationabsorption and/or emission profiles. In certain instances, one or moreligands bound to the lanthanide and/or actinide act as antennasharvesting electromagnetic radiation. In some instances, the emissiveproperties of an emissive species comprising a lanthanide may vary uponthe binding of water. In certain cases, the effects of water may bemitigated by substituting heavy water (i.e., D₂O) for H₂O. In certaincases, an emissive species may be prepared by binding heavy water to alanthanide and/or actinide, and the emission lifetime may be reduced todifferent degrees by exchange with water. Such a process may be used, insome cases, to determine if a material has been exposed to an atmospherecontaining water vapor.

Purely inorganic phosphors may also be excited by the light sources of asmartphone. In some cases, the absorption efficiency on a weight basismay be lower than some of the organic materials, however these materialsmay advantageously display high thermal and chemical stability. Purelyinorganic phosphors often contain different oxide materials (aluminate,silicate, borates) that have high melting points and can be classifiedas ceramics. They may also be dispersed in other salts, includingfluorides or sulfates. The luminescent properties may arise, in somecases, from the integration of active metal ions into inorganicmaterials. Such structures can be organized as single crystals or may beconsidered to be solid solutions. For example, Cr⁺³ can be incorporatedinto a matrix of Al₂O₃ and these compositions, generally referred to asruby, display phosphorescence and can be excited by the light source ofa smartphone. There are many other active elements that can be placed ininorganic materials, and some can be in different oxidation states.Non-limiting examples of suitable metal ions that can be used to createinorganic phosphors include Eu, Bi, Ce, Cr, Nd, Yb, Pb, Gd, Dy, Er, L,U, Ta, Sr, and Y.

In some embodiments, multiple metal ions are incorporated into acomposition to create an inorganic phosphor. The excited state lifetimesof these materials, depending upon the material, may be characterized asprompt-phosphorescence or delayed-phosphorescence and thereby may beuseful for producing non-steady-state photon emission events. Differentelemental substitutions may affect lifetimes and as a non-limitingexample the substitution of Mn⁺² into different compositions may be usedto create extended excited state lifetimes.

A number of inorganic phosphors belong to the structural class ofcompounds called perovskites and may also be suitable in accordance withembodiments described herein. In these types of compounds, there isoften an atom that is viewed as a cation between different polyhedralgroups, often composed of metal oxides or halides. A sub-area ofperovskites are materials wherein the cations are organic ammonium ions.Some of these organic/inorganic hybrid salt complexes, which are readilysynthesized at low temperature, and may be excitable by smartphones.Non-limiting examples of smartphone excitable crystals include(n-butylammonium)₂PbI₄ and (N-methylpropane-1,3-diammonium)PbBr₄. Theexcited lifetimes of these organic/inorganic hybrid perovskites may varyfrom those corresponding to prompt-fluorescence andprompt-phosphorescence and are generally capable of producingnon-steady-state photon emission events. Longer excited state lifetimesmay also be possible with different compositions (e.g., with elementsmore environmentally friendly than lead).

Another class of purely inorganic emissive species are those createdfrom nanostructured semiconductors and may also be suitable inaccordance with embodiments described herein. There are many differenttypes of these materials and without wishing to be bound by theory, as aresult of their delocalized electronic states, the size of thenanoparticles may be correlated with their absorption characteristics.As such, in some embodiments, selected sizes of these materials may beused to create smartphone excitable materials. A non-limiting list ofsemiconductive nanomaterials include nanoparticles comprising one ofmore of the following, CdS, CdSe, CdTe, ZnSe, InP, Ge, PbS, and PbSe.The excited state lifetimes of these materials may vary with size andcomposition and materials displaying excited state lifetimescorresponding to those of prompt-fluorescence to prompt-phosphorescencehave been observed.

Metallo-organic analogs of Eu⁺³, Tb⁺³, and other lanthanide or actinideelements may display delayed-phosphorescence, in some cases. In someembodiments, the organic ligands interacting with the metal centerbehave as antennas for the capture of photons. Without wishing to bebound by theory, the ligands once excited to their singlet excitedstates, generally undergo a rapid intersystem crossing to a tripletstate, and then transfer triplet energy to the metal center. Therelative energies of the triplet states and those on the metal centermay affect the efficiency of the energy transfer. As a result, careshould be taken to select ligands that are excitable by a smartphone andmay efficiently participate in triplet energy transfer to the metalcenter. The orbitals on the metal centers are contracted and theelectronic states may be considered to be heavily localized on the metalcenters, in some cases. As a result, the emission spectra may be verysimilar from different complexes of a particular metal, even with verydifferent antenna ligands and coordination environments. Ligands may beselected to have other desirable properties, including sensitivity todifferent chemical, thermal, optical, environmental, and/or opticalstimuli.

Europium (Eu⁺³) based emitters are of particular note in accordance withembodiments described herein as they generally display red lightemission. Antenna ligands capable of absorbing light from the lightsource of a smartphone may be used. A non-limiting example is the ketonecomplex described below. The ketone is generally a non-ionic ligand andis generally more weakly bound than the other three anionic1,3-diketonate ligands. In some cases, the coordination sphere aroundthe Eu⁺³ may be dynamic and additional ligands, shown as L, may alsocoordinate to the metal center. Without wishing to be bound by theory,the degree of coordination is generally subject to the stericconstraints around the metal center and those imposed by the ligands.The steric influence of matrix materials may also play a role, in somecases. For example, in some embodiments, two ketones may be interactingwith the Eu⁺³ center or that there is no L coordinated. The L groups maybe anionic and, for example, may be a carboxylate, sulfate, or halideion. The weakly bound nature of the ketone generally causes it to besusceptible to substitution. In cases where a more robust association isrequired, the matrix material may be used to enforce a strongassociation by restricting the geometry and/or by placing the materialsin a highly rigid environment. In some applications, it may be useful tohave the ketone metal interactions be subject to modulation by chemical,optical, thermal, environmental, ionizing radiation, and/or mechanicalstimulation. These applications may, for example, take advantage of theweak binding of the ketone to the Eu metal center. Such changes can beirreversible or reversible, depending on the application. Other ketonesbeyond those shown, as well as other ionic ligands, may also be used tocreate smartphone excitable complexes.

Anionic ligands associated with the metal centers may be used, in somecases, to create a diversity of materials with delayed-phosphorescence.A non-limiting example of a smartphone excitable Eu⁺³ complex that has acarbazole integrated into the ionic 1,3-diketonate ligand is shownbelow. In some embodiments, without wishing to be bound by theory, theextension of the π-electron system by the carbazole allows this compoundto be excited by a smartphone. The neutral 1,10-phenanthroline ligandgenerally occupies two coordination sites on the Eu⁺³ as shown. Anadditional ligand to be bound to the Eu site is also possible. In someembodiments, a number of other ligands may be paired with the carbazole1,3-diketonate ligand shown (e.g., enhancing the absorption of lightfrom the smartphone, and/or create the opportunity to excite the complexat an alternative wavelength).

Non-limiting examples of Europium complexes with anionic ligandscontaining fused aromatic rings (such as phenanthrenes andtriphenylenes) that may be excited by visible light are shown below.Without wishing to be bound by theory, incorporation ofvisible-light-absorbing moieties into anionic ligands yields generallyimproves white light activated phosphores since the ionic ligands aremore tightly bound to the Eu⁺³ than neutral ligands.

A non-limiting example of an Eu⁺³ complex having a tricoordinate antennaligand is shown below. This is only one of a number of potential analogsthat are possible and one of ordinary skill in the art will understandbased upon the teachings of this specification that differentsubstitutions may be used to enhance the absorption of light from asmartphone (or other consumer electronic device), the compatibility withmatrix materials, the stability of the complex, prevent unwantedquenching, and/or enhance the quantum yield of thedelayed-phosphorescence.

Additional suitable non-limiting examples of Europium based emitters areprovided herein, in Examples 8-21 below, and some exemplary structuresare shown in FIG. 35A.

Other smartphone excitable materials capable of displayingdelayed-phosphorescence include the boron and aluminum complexes shownbelow. These materials generally have very rigid structures thatrestrict non-radiative relaxation of their excited electronic states tothe ground state. Without wishing to be bound by theory, the lack ofheavy atoms generally results in slower emission rates than would beexpected with the incorporated heavy atoms. Nevertheless, such materialsmay display strong luminescence if incorporated into an appropriatematrix. The long lifetimes of these compounds give rise to oxygenquenching and these materials may therefore be used, for example, asoxygen sensors.

In many applications the smartphone excitable luminescent materials(e.g., emissive species) may be suspended in another material (e.g., amatrix). The luminescent materials may be in a fluid or solid solutionwherein they are randomly dissolved at the molecular level. Crystals orparticles of the luminescent materials may be dispersed in a solid, thinfilm, liquid crystal, oil, or solution. Luminescent materials can beco-crystallized with another material. Luminescent materials may beimbibed into a polymer or plastic by thermally promoted diffusion, byphysical pressure, and/or by solvent assisted transport into thematerial. Materials may be prepared by polymerization of monomersincasing the materials in a dispersion or as a bulk material/film.Luminescent materials may be attached to materials by adhesives,including pressure sensitive adhesives, epoxy resins, polyurethanes, orthermoplastics. Polymer encapsulants may be applied to dispersions ofluminescent materials to create coated particles. Luminescent materialsmay be synthesized in a matrix material that may be either organic orinorganic in nature.

In some embodiments, luminescent materials may be used in aqueousenvironments and may be connected (conjugated) to other species,including biological recognition elements such as proteins, antibodies,DNA, and RNA. They may also be directly connected to fungi, bacteria,tissue, or cells. Materials may be dispersed in solutions or powder formand polymers may be assembled around them to create coated polymers. Forexample, if a luminescent material is relatively non-polar it may bedispersed in water using polymer, molecular, or polymerizablesurfactants. Polymers of the structureZ(OCH₂CH₂)_(x)(OCH(CH₃)CH₂)_(y)(OCH₂CH₂)_(x)OZ may be used to dispersematerials. This block copolymer has a hydrophobic group in the centerthat may interact with the hydrophobic luminescent material, while the(OCH₂CH₂)_(x) groups are generally hydrophilic allowing for waterdispersibility. The Z groups, which may be more than one functionalitymay be used to crosslink the materials to form robust coatings and/or toconjugate them to another material, such as an antibody, protein, orDNA/RNA. There are many types of suitable polymer surfactants anddiblock copolymers of polystyrene with other polar materials includingacrylates of poly(ethylene oxide) that represent non-limiting examples.It is also possible to disperse luminescent materials in a polymerizablemonomer to create polymer encapsulated materials. For example, aluminescent material may be dispersed in water by the use of asurfactant with styrene to create particles. The luminescent materialmay be dispersed uniformly in the polymer particle as a solid solutionor separated into small crystals or aggregates. In some cases, the actof polymerizing a material hosting the luminescent material may causethe material to separate to give embedded crystals or aggregates.Comonomers may be used to crosslink the polymers or to create functionalgroups on the surface of the particles that may participate inbioconjugation reactions. The functional groups may also be added postpolymerization as needed. Preferred, non-limiting functional groups thatmay be placed on the surface of a particle incorporating a luminescentmaterial include carboxylic acid groups, amines, thiols, esters,alkenes, strained cyclic alkenes, strained cyclic alkynes, electrophilicalkenes, maleimides, tetrazines, isothiocyanates, blocked isocyanates,oxazolines, carbodiimides, or azides. A diversity of methods (reactionsequences) are available that use these groups to create linkages todifferent biomolecular species.

In some embodiments, a pre-existing polymer particle may befunctionalized with a luminescent material. An illustrative butnon-limiting example is the case of polystyrene particles that havecarboxylate groups on their surface. Dispersing these particles in asolvent that swells the polymer, such as methylene chloride, chloroform,tetrahydrofuran, toluene or 1,2-dichlorobenzene but also contains theluminescent material may be used to make luminescent particles. In someembodiments, once the particles are swollen with the organic solutioncontaining the luminescent material, the materials are dried. If none ofthe materials are soluble in water, the particles may be dissolved inwater and methods for conjugation to different biomolecular recognitionelements applied. Conjugation methods include reactions of amines withreactive esters, thiol additions to alkene acceptor molecules(thio-Michael reactions), click reactions between tetrazine and reactivealkenes, amine additions to isothiocyanates, copper-catalyzed clickreactions of organic azides with terminal alkynes, and/or clickreactions of organic azides with strained cyclic alkenes and alkynes.

Functional groups may be added to the materials, or particles containingthe materials, that may covalently link the materials to the object ofinterest. Luminescent materials may be bound to a tape and added to anarticle by lamination. High temperature processes may be applied topurely inorganic materials that allow for reaction or fusion with glass,ceramics, or polymers. Some materials may be capable of sufficientlyhigh temperatures such that they may be thermally imbibed into glass. Insome applications, mixtures of multiple luminescent materials aredesired. In other cases, one or more luminescent materials may bespatially patterned on an article. Spatial pattering may be done in allthree dimensions and may be accomplished by, for example, lamination,spray coating, screen printing, gravure printing, ink jet printing,embossing, stamping, or 3D printing.

After fabrication, the materials may potentially be locked in a finalstable form by heating, polymerization, photolysis, lamination, or byovercoating. The materials may also be passivated via encapsulation.

In some cases, electron transfer processes may be used to creatematerials with emission lifetimes that may be used to encode informationin or on articles. In some cases, these processes include the use ofelectron transfer processes to create excited states.

In some embodiments, an emissive species may be used as crystals,ceramics, particles, in polymer composites, and/or encased in glass. Insome embodiments, an emissive species is deposited on an object with acontinuous composition, gradient, or pattern. In certain instances, apattern may be similar to linear bar codes or matrix codes that arereadable by laser scanners or image analysis. In some embodiments, oneor more emissive species are directly integrated into a printed image ormixed with other dyes. In some embodiments, one or more emissive speciesare homogeneously deposited on a solid, surface, or solution. A personof ordinary skill in the art will recognize that emissive species may beadded to compositions or deposited in patterns with other emissive orcolored materials to create unique and complex information content.

The emissions detected may depend on the excitation method, frequencies,delays, wavelengths, and intensities of the emissive species that arepresent. Delays after a pulse may change the image, which may beparticularly apparent if multiple emissive species are spatiallypatterned. In some cases, all emissive species may be excitedsimultaneously. In some cases, certain emissive species may beelectively excited by the choice of wavelength of electromagneticradiation used. In some cases, an article may have an intrinsicemission. For example, a printed object may use blue dye to preventpaper or fabric from appearing yellow. Emission from these brightenersmay be blocked by printing or depositing materials over them. Forexample, carbon-based inks may be deposited on white paper. Similarly,longer lived emissive species may be deposited on paper and thenpatterned by printing carbon inks on top of them.

In some embodiments, a secondary process may occur that quenches anemission. In some embodiments, an emissive material may contain anemissive species that may be read only once or a few times. For example,a secondary process could be initiated by the reading process thatcauses an irreversible change in the article containing the emissivespecies. This change may be immediate or take some time to develop. Suchchanges may be activated by photochromic molecules, and/or thephotogeneration of acid, base, radicals, or quenchers. In some cases, anemissive species may be configured to produce a detectable emission, buta secondary process may change the material such that the detectableemission is not present with repeated reading. In some cases, asecondary process may be triggered by photochemical generation ofreactive molecules, colored dyes, radicals, acids, bases, reduced oroxidized species, and/or causing a chemical cascade. Secondary processesmay also be initiated by mechanical stress, air exposure, moistureexposure, or ionizing radiation such as gamma rays or x-rays.

The abundance of different emissive species makes it possible to createmany different response mechanisms for not only determining theintrinsic identity of a material, but its chemical state. Many of theemissive species described herein are multicomponent with bonds,associations, and/or linkages that may be modified to give a reversibleor irreversible response to light, temperature, radiation, a molecule ofinterest, an enzyme, a nucleic acid, a protein, a cell, a bacteria, avirus, a spore or other biomolecule, physical modification, pressure,gas, oxygen, moisture, carbon dioxide, pollen, environmental pollutant,particulate, drug, pH, allergens and the like.

In some embodiments, one or more, two or more, three or more, four ormore, five or more, six or more, seven or more, eight or more, nine ormore, ten or more, fifteen or more, or twenty or more (different)emissive species may be present (e.g., associated with an article, inthe system, on a chemical tag, on a label) and/or excited by anexcitation component. In some embodiments, the number of differentemissive species associated with an article is in a range from 1 to 2, 1to 5, 1 to 7, 1 to 10, 1 to 15, 1 to 20, 2 to 5, 2 to 7, 2 to 10, 2 to15, 2 to 20, 5 to 7, 5 to 10, 5 to 15, 5 to 20, 10 to 15, or 10 to 20.In some embodiments, each emissive species may be responsive (e.g., maychange in one or more of an intensity of the emitted light, apolarization of the emitted light, a spatial profile of the emittedlight or a change in the emission lifetime of the emissive species) todifferent stimuli (e.g., change to a particular temperature, pH,solvent, chemical reagent, type of atmosphere (e.g., nitrogen, argon,oxygen, etc.), electromagnetic radiation). In some such embodiments, acharacteristic of the stimuli (e.g., presence, identity, etc.) and/orarticle may be determined based upon which one or more emissive speciesproduce(s) a detectable signal.

By way of illustrative example and without wishing to be limited assuch, in some embodiments, a system comprises a first emissive speciesand a second emissive species. In some embodiments, a determinablechange in the first emissive species (but not the second emissivespecies) corresponds to a particular characteristic (e.g., of an articleassociated with the emissive species). In some embodiments, adeterminable change in the second emissive species (but not the firstemissive species) corresponds to a particular characteristic. In someembodiments, a determinable change in both the first emissive speciesand the second emissive species corresponds to a particularcharacteristic. In some embodiments, no determinable change in eitherthe first emissive species or the second emissive species corresponds toa particular characteristic. In some embodiments, a third emissivespecies is present. In some embodiments, a change in one of the threeemissive species corresponds to a particular characteristic. In someembodiments, a change in two of the three emissive species correspondsto a particular characteristic. In some embodiments, a change in threeof the three emissive species corresponds to a particularcharacteristic. In some embodiments, no change in three of the threeemissive species corresponds to a particular characteristic. Those ofordinary skill in the art would understand, based upon the teachings ofthis specification, that higher order combinations of emissive species(four or more, five or more, etc.) may be used and that select changesin select emissive species may corresponds to a particularcharacteristic(s) (e.g., of an article associated with the emissivespecies).

By way of a further illustrative example and without wishing to belimited as such, in some embodiments, a system comprises a plurality ofemissive species (e.g., at least a first emissive species, a secondemissive species, and a third emissive species) such that each emissivespecies is selected to be responsive to a particular stimulus. Forexample, the stimulus may be concentration of an analyte, pH, and/ortemperature. In an exemplary set of embodiments, each emissive speciesmay be responsive (e.g., the emissive species undergoes a propertychange such as wavelength and/or intensity) to a different temperature.In some such embodiments, a change in one or more emissive species isindicative of exposure to a particular temperature (or set oftemperatures). For example, a change in the first emissive speciesindicates exposure to at least a first temperature, and a change in thesecond emissive species indicates exposure to at least a secondtemperature, different than the first temperature. Other stimuli arealso possible, as described herein.

In some cases, information may be extracted from a subset of thedifferent emissive species by the use of complex excitation methods,polarization, spatial patterning, time delays, and/or secondaryexposures.

FIG. 7 shows an exemplary system comprising two emissive species. In theexemplary system shown in FIG. 7 , one emissive species has an emissionlifetime greater than 10 ns, and one emissive species has an emissionlifetime less than 10 ns. As shown in FIG. 7 , the rolling shuttereffect may be combined with a pulsed electromagnetic radiation source toresolve the individual components. FIG. 7 (left) shows an opticalmicrograph of a vial containing two emissive species. FIG. 7 (middle)shows an optical micrograph of the same vial under pulsed illuminationimaged using rolling shutter. As shown in FIG. 7 (middle), during the“on” state, emission from both species is observed, and during the “off”state, only emission from the species with an emission lifetime greaterthan 10 ns is observed. As may be seen from the magnified image shown inFIG. 7 (right), the rolling shutter method superimposes the time domainon the spatial domain.

The systems and methods described herein may be useful for a number ofapplications. For example, in some embodiments, the systems and methodsdescribed herein may be used for product identification, productauthentication, or the like. In some embodiments, the systems andmethods described herein may be used to determine a characteristic of anarticle. In some instances, the characteristic of the article mayinclude the identity of the article, point of origin of the article, thelocation of the article, the authenticity (or counterfeit nature) of thearticle, the quality of the article, the age of the article, whether thearticle is new or used, deterioration of the article, mishandling of thearticle, tampering of the article, contamination of the article, or thelike. Such characteristics may be useful for, for example, detectingtheft, detecting unauthorized distribution, identifying illegal sales,identifying counterfeit products, identifying adulterated products,quality control, quality assurance, tampering with, and tracking of thearticle.

Optimization may involve, in some embodiments, creating a set ofparameters that maximizes the signal and/or minimizes (suppresses) thebackground (e.g., including stray light) signals. These parametersgenerally depend on the particular assay and conditions under which thereading is conducted. When deployed on a smartphone a colorimetricsignal may be used to provide information that directs the user toorient the smartphone in a particular manner relative to the assay togenerate a desired signal. In some cases, this information, which can becontained in a picture, logo, QR code, or bar code on the assay informsthe smartphone about the optimal camera settings such as shutter speed(exposure time) and/or sensitivity (ISO) setting and the excitationprofile. In some cases, the phone may perform measurements that rapidlyexplore a range of values for the shutter speed/ISO and thetype/duration of excitation to be used. Computationally, the smartphonemay be used to determine imaging conditions that produce desired signals(e.g., by providing high definition/contrast, the rejection of artifactsand stray light, and producing bright emissive signals). It may be thatthe data collected during this survey is adequate and optimal signalscan be extracted from many images. It may be that all images are fusedtogether, in some embodiments, such that only a fraction of the imagesare used to create the measurement. It may also be the case that guidedby a quick survey method, computational methods yield imaging parametersthat configure the smartphone to make subsequent measurements using aparticular set of parameters to create an optimal measurement. Forexample, this may be used to determine if the assay is moved away from abright interfering light source or change the time over which each imageis collected by the detection chip (shutter speed or exposure time), orhow best to configure the excitation. The latter may be pulsed lightflashes or a frequency modulated method. In some cases, the smartphonemay instruct the user to seek conditions that limit ambient light. Thismay be accomplished, for example, by going into a dark room or closet orusing a dark cover over the camera and assay to eliminate light. Thelatter may comprise a dark cloth, piece of black plastic, or a boxcapable of positioning the camera relative to the assay while blockingstray light from interfering with the measurement. The latter maycomprise a disposable element provided as part of product packaging.

In some embodiments, an emissive species (e.g., a phosphor) may be usedto detect the presence of a heavy metal (e.g., lead, mercury). As anillustrative example, an emissive species (e.g., a lumophore) may becoated on a strip of paper, and the coated paper may be inserted in awater sample. If heavy metals are present, they may bind to the coatedpaper and may modify the emission lifetimes of the emissive species. Theemission lifetime of each species may be measured using lifetime imagingas described above.

In some cases, a test strip (e.g., an emissive species coated on a stripof paper) may be used to detect a molecular signature of a product. Asone non-limiting example, a perfume may be sprayed on a test strip toproduce a new object that, when imaged over the lifetime of the emissivespecies, may be used to validate its identity. The molecular signaturemay be caused by selective enhancement or quenching of emissive speciesand/or changing the lifetime of emissive species.

In some cases, an emission tag (e.g., a chemical tag) may be used forlabeling or information encoding. In some cases, such emission tags(e.g., chemical tags) may rely on patterning and different colors. Theemission images may be prepared and read by a number of possible complexand variable excitation and measurement methods. In some cases, manydifferent image patterns may be generated by a single emission tag. Themeasured lifetime images may be dynamically changed based on anapplication or from instructions transmitted to the reading device froma central source. Complex algorithms may be assigned to a given locationor the time of day where the image is acquired. In some cases, secondaryinformation (e.g., a one- or two-dimensional bar code on an object) maycontain instructions on how to read a complex emissive lifetime image.

In some cases, a dynamic quencher that is capable of quenching selectemissive species to produce a specific lifetime may be added to anemissive material. Emissive species and/or dynamic quenchers may beincorporated in films, bulk polymers, pastes, gels, or fluids (e.g.,liquids, gases). For example, one or more emissive species may beprinted on a surface, and one or more dynamic quenchers may be placed ina gas phase. In some cases, the rate of diffusion of the quencher may bemodified by a secondary stimulus, and a lifetime image may be used todetect the presence of the secondary stimulus. The stimulus may bechemical, thermal, photochemical, radiative (e.g., involving exposure toionizing radiation), or mechanical. The action of the secondary stimulusmay be reversible or irreversible. If reversible, it may behave as areal-time sensor for the second stimulus. Non-limiting examples of asuitable secondary stimulus include the presence of water and heat. Heatis well known to modify the diffusion processes within materials and canmodify the lifetime of an emissive species by changing the diffusionrates of dynamic quenchers. It may also involve selective excitation ofa photochromic element. Electromagnetic radiation may be used to changethe properties of the materials and their diffusion. The secondarystimulus may also be used to increase the concentration of the dynamicquenchers, which may increase the probability that the dynamic quenchersare close to the emissive species. In some cases, both the dynamicquencher and the emissive species may diffuse. In some cases, only theemissive species may diffuse. The encounter of the two species isgenerally controlled by diffusion rates and concentration.

In some cases, an article may be associated with an emissive tag (e.g.,a chemical tag) that is difficult to reverse engineer or copy. In anemissive tag, a plurality of different emissive species may be placed indifferent environments, positions, or orientations by the way thecompositions are assembled. In some embodiments, the process by which anemissive tag is assembled may be complex and may yield a unique signal.It is far easier to create a new unique signal in a highlymultidimensional processing space, than it is to replicate this signal.Hence, it will be efficient to create new unique signals, and will beeffectively futile to attempt to counterfeit copies of thesecompositions. In some embodiments, emissive species may be covalentlybound and/or encased in materials that can only be disassembled byaggressive physical, thermal, and/or chemical processes that result indegradation of the emissive species. This may, in some cases, preventeasy identification of the emissive species. In addition, the patternscreated may be sufficiently complex that significant effort would berequired to reverse engineer or copy the patterns. Moreover, even if anemissive tag could be reverse engineered or copied, codes may be easilychanged and require matching to other product information, such aslinear barcodes and/or matrix codes.

One way to authenticate an article is to place specially designedemissive species directly within the article. Emissive species may beembedded in plastics, ceramics, glass, metals, paints, gels, waxes,liquids, or oils. In some cases, the emissive species may behomogeneously distributed. In some cases, the emissive species may beprinted according to a pattern. Even in the absence of a complexpattern, given the possible variations in emissive species colors andemission lifetime, there is still considerable information available.

Additionally, a secondary label on the container that a product (e.g.,an article) comes in may be used to give the reader (e.g., a smartphone)additional instructions on how the read is to be performed. For example,a fluid may be analyzed by first scanning an optical linear barcode ortwo-dimensional matrix code on its container or packaging and thenscanning the fluid. In such a way there may be a variety of codescreated for products with minimal expense. In another representativeexample, a liquid, gel, paste, or solid containing a taggant may besprayed or deposited onto a linear barcode, two-dimensional matrix code,a test strip capable of creating a non-steady state photon emission toproduce an image, or any other region of the container or packagingcapable of recognizing the presence of the taggant. In such a way theauthenticity of both the contents and its associated packaging may beeasily verified.

A wide variety of emissive species may be produced from non-toxicorganic and/or inert inorganic materials. Similarly, insolublecarbon-dot materials may be considered as non-toxic, thermally stable,and inert. In some embodiments, these materials need only be present intrace concentrations and may be applied to the skin in the case inperfumes and cosmetics. Alternatively, the emissive species may be partof the coating on a product. In the case of coated pills, tablets, orcapsules, combinations of emissive species can uniquely encode the pill,tablet, or capsule while remaining safe for consumption. In some cases,one of more safe materials that are approved for human consumption orfor application to the skin may be combined. For example, bismuthcompounds are used in treating digestive problems. Bismuth may be usedto create compositions with edible dyes to create long-lived emissivecomplexes. Other suitable non-limiting examples include food dyes thatcan have long-lived emissions. Advantageously, long-lived emissions mayenable, in some cases, selective detection by non-steady-state methods.

Emissive species can be included in other consumable materials such aslubricating oils.

Emissive tags may be incorporated onto packaging, in the packagingmaterial itself, integrated as part of a linear barcode or matrix code,or included in an image or trademark. The linear barcode or matrix codemay provide instructions to the reader on how to excite the emissivespecies and where to read the code. For example, in a given package, auser may be instructed to place his or her reader (e.g., image sensor)over a particular symbol or word. It is possible that there could bemultiple codes placed on a single package and the reader only redirectedif there was data suggesting possible counterfeit activity. This couldbe the result of optical barcodes suggesting that a product was notdistributed in a particular region, but there are multiple productsbeing read in that area. It could be that other questionable codes thatare potentially counterfeit have been detected. Thus, the use ofemissive species may advantageously provide a low-cost way ofincorporating authentication information into the packaging of a productthat may also be used to obtain information to track the sources ofcounterfeit goods.

Packaging is often used to protect a product from the environment, andemissive tags may be used to determine the status of the product. Insome cases, an emissive tag may be designed to respond to particulartypes of stimuli. For example, if an emissive tag is placed on theinside of food packaging, it may be used to determine the quality of thefood. Biogenic amines produced by microbial activity could cause changesin emissive species responses (e.g., lifetime, intensity, wavelength ofthe emission, color) and the concentration of these amines determined bythe captured image. In some cases, this measurement may be determinedwithout ever opening the packaging provided the packaging is transparentat the tag excitation and read wavelengths. Similarly, for modifiedatmosphere packaging used for produce, tags may be developed that detectthe levels of oxygen, carbon dioxide, and/or other microbial markers.The ingress of oxygen may be used to determine if the seal of a producthas been broken.

In some embodiments, emissive tags may be used to sense gas and/orliquid states. In some embodiments where a product is a liquid, theemissive tag may be in contact with the liquid, and specificinteractions between constituents of the liquid and the emissive tag maybe used to generate a unique image read by emission wavelengths andlifetimes. For blister packaging and the like, an analyte may beincorporated into the contents of the item contained within thepackaging for subsequent release, or actively added at the point ofmanufacture to the head-space of the packaging, such that the resultanthead-space analyte interacts with an emissive tag located on the insideof the packaging to affect the emissive wavelengths and lifetimes of thetag. In one embodiment, this analyte-tag interaction may be reversible,such that the tag reverts to its original state upon opening the packageand the subsequent evaporation or removal of the analyte.

In some cases, the thermal history of the product may be determined bythe emissive authentication code placed in or on the packaging. This maybe very useful for thermally sensitive medications such as biologics,insulin, and vaccines. Emissive tags may be used to determine theauthenticity of products and ensure that the cold chain, needed topreserve their quality, has been observed. In one embodiment, anemissive tag located on a vial of insulin may be used to monitor thecumulative time-out-of-fridge. Thermal history tags may also be usefulto monitor the quality of meat and fish as well as wine.

The combination of an emissive encoded tag, optical linear barcode ormatrix code, hologram, embossed code, waveguided code, and a smartphonereader or similar interconnected device, may be used to obtain time,location, and authentication data. This data may be captured locallyusing a device application and periodically transmitted to a centrallocation or, bandwidth permitting, be constantly transmitted. In somecases, manufacturers and/or retailers may be able to use thisinformation to monitor where their products are located and, moreimportantly, where counterfeit products are infiltrating their supply ordistribution chains.

In some embodiments, an emissive tag is optically anisotropic. In someembodiments, one or more emissive species of an emissive tag may emitelectromagnetic radiation at a first set of wavelengths and emissionlifetimes in one direction and a second set of wavelengths and emissionlifetimes in a second direction. In some cases, this anisotropy may beproduced by mechanical methods (e.g., blow molding, melt flow,extrusion, rubber, embossing, solvent flow, stretching) when theemissive species is a polymer or is embedded within a polymer. In someembodiments, emissive species may be part of a liquid crystal ordissolved in a liquid crystal. Alignment of emissive species within theliquid crystal may be accomplished by mechanical methods, opticalmethods, photochemical reactions, and/or the application of electricaland/or magnetic fields. In certain cases, circularly polarizedelectromagnetic radiation may be generated. In some cases, thesealignments may be retained and persist in the emissive tag indefinitelyor until other conditions are applied that cause a loss of alignment. Incertain cases, an anisotropic optical material may be placed aroundand/or over an emissive species and may thereby generate a polarizedimage. In some cases, the addition of polarization and opticalanisotropic character to an emissive tag may advantageously createadditional complexity and provide more options for encoding information.In some cases, an increase in temperature may cause a decrease inoptical alignment within a material. In some such cases, emissivelifetime image changes resulting from a change in the alignment of amaterial may be used to obtain information on the thermal history of anobject.

In some embodiments, pills, tablets, and capsules may be placed in ablister package. Typically, one side of this package is hemisphericaland transparent so that the product may be seen and the backing, oftenfoil, is flat with the product removed by breaking the backing. Thesepackages may contain atmospheres that result in specific lifetimes foremissive tags. The atmosphere may contain a gas such as carbon dioxide,which may interact with amines or other species in the emissive materialto give a unique lifetime. This may yield a unique optical signature forthe product. In some cases, if the product is compromised by breakingthe seal, this may also be detected. In some embodiments, the atmospheremay be nitrogen or argon, and the emissive tag may be one that changesits lifetime in the presence of oxygen, which may infuse into thepackaging if the seal is broken. In some instances, the atmosphere maycontain heavy water, which may be replaced by water in the event of abroken seal.

In some embodiments, an emissive species and/or emissive tag may becombined with recognition entities such as RNA, DNA, PNA, chimericnucleic acids, molecular beacons, antibodies, aptamers, lectins,proteins, engineered proteins, enzymes, intercalating agents and thelike to produce assays (e.g., diagnostic assays, immunoassays). In somecases, the assays may be used for point-of-care, field, point-of-need,and/or in-home diagnostic use. In some embodiments, the assays may bebased on high-throughput screening (HTS), time-resolved FRET, and/ortime-resolved fluorescence quenching techniques. In certain cases, theassays may be combined with other diagnostic, sensing, and/orsignal/analyte amplification techniques, including but not limited topolymerase chain reaction (PCR), quantitative polymerase chain reaction(qPCR), isothermal amplification, gene editing techniques, and the like.In certain cases, the assays may be combined with high-throughput arraytechniques, including but not limited to DNA microarrays, proteinmicroarrays, organ-on-a-chip devices, and the like. In some cases, theassays may be used to test environmental samples (e.g., water, soil,mold, paint) and/or biological samples (e.g., blood, sweat, mucus,urine, stool). In some cases, these assays may be incorporated intowearable sensors designed to monitor pH, sweat rate/loss, theconcentration of analytes (e.g., glucose, lactate, chloride,electrolytes, metabolites, small molecules). In some cases, the systemsand methods described here may be fabricated into assays (e.g.,diagnostic assays) to monitor analytes indicative of disease states suchas bacterial, viral, or fungal infections, renal failure, or cancer. Onewho is skilled in the art will recognize that other assays are possible.

In some embodiments, emissive sprays, aerosols, liquids, particles andthe like may be used to verify the presence or absence of allergens infood and drink samples. In some embodiments, emissive solids, liquids,particles, aerosols, gels, pastes or the like may be widely distributedand remotely monitored to verify the presence or absence of analytessuch as explosives, chemical agents, biological agents, toxic chemicals,heavy metals, narcotics, radiation and the like. Additionally, theaforementioned rolling shutter effect can yield distance information forrange-finding applications.

In another embodiment, emissive tags capable of detecting analytes suchas explosives, chemical agents, biological agents, toxic chemicals,heavy metals, narcotics, radiation and the like may be deployed onautonomous air, land, and sea based vehicles for remote monitoring.

In another embodiment, emissive tags may be used for friend/foeidentification.

In another embodiment, emissive tags may be used in security badges oridentification cards.

In another embodiment, emissive tags may be used in currency.

In some embodiments, an emissive species (e.g., a chemical and/orbiological species) described herein may be associated with apoint-of-care, field, point-of-need, or home diagnostic kit or relatedmethod.

In some embodiments, one or more emissive species may be incorporatedinto a solution that is drop-casted, spun-coat, or sprayed onto avariety of substrates. In some embodiments, an emissive species may beincorporated into a thin film.

In some embodiments, the systems and methods described herein may beused to detect degradation (e.g., a characteristic) of an article dueto, for example, exposure to extreme temperatures, changes in moistureand/or humidity, exposure to light and/or chemical reactants). Forexample, in some such embodiments, the one or more chemical and/orbiological species may have a time-dependent emission and/or reflectionbehavior that is altered by exposure to different temperatures,moisture, humidity, light, and/or reaction with particular chemicals. Inother cases, the chemical and/or biological species may be used as atimer to ensure the quality of a material. For example, if the change inthe characteristic of the species is triggered by exposure to gammaradiation, ethylene oxide, oxygen, or other sterilization agents as partof a sterilization process, then the emissive species may be used toindicate the exposure and/or how much time has expired after thisprocess. Similarly, a physical opening of packaging around an articleand exposure to ambient atmosphere may be identified (e.g., acharacteristic) using the methods and systems described herein.

In some embodiments, as described herein, changes in the emissionprofile (e.g., amount, rate) of an emissive species (e.g., as identifiedin a single image), under a particular set(s) of conditions, correspondto one or more characteristics of an article or the species itself. Thatis to say, in some embodiments, one or more characteristics of anarticle may be identified based upon the luminescence and/orreflection/scattering profile of one or more chemical and/or biologicalspecies (e.g., chemical and/or biological species proactively added tothe article).

In some embodiments, the species may be applied to an article and arecord of the characteristic of the article associated with that speciesmay be made. For example, in some embodiments, the identity of thearticle may be confirmed if a particular emission pattern is detected byan image system.

In some embodiments, the systems and methods described herein may becombined with one or more additional identifying components. Forexample, in some embodiments, a second identifying component, differentthan the chemical and/or biological species, may be present. Forexample, in some embodiments, the species may be further associated witha single or multidimensional optical barcode. Those of ordinary skill inthe art would understand, based on the teachings of this specification,how to select additional identifying components for use with the methodsand systems described herein. In some embodiments, the article isassociated with a species and a second identifying component such as anoptical barcode, hologram, RFID, and/or additional chemical markersand/or biological markers. Non-limiting examples of additional chemicalmarkers and/or biological markers that may be used in conjunction withthe systems described herein include, but are not limited to,colorimetric dyes, fluorescent dyes, IR dyes, watermarks, nanoparticles,nanorods, quantum dots, antibodies, proteins, nucleic acids, andcombinations thereof.

The term “associated with” as used herein means generally held in closeproximity, for example, a chemical tag associated with an article may beadjacent a surface of the article. As used herein, when an emissivespecies is referred to as being “adjacent” a surface, it may be directlyadjacent to (e.g., in contact with) the surface, or one or moreintervening components (e.g., a label) may also be present. A chemicaltag that is “directly adjacent” a surface means that no interveningcomponent(s) is present. In some embodiments, the chemical and/orbiological species is adjacent a surface of the article. In someembodiments, the emissive species is directly adjacent a surface of thearticle. In some embodiments, the emissive species is incorporated intothe article (e.g., is present within the bulk of at least a portion ofthe article but, absent the addition of the chemical and/or biologicalspecies to the article, would not be inherently present in the articleitself or not present in an amount desirable for implementation of thesystems and/or methods described herein).

In some embodiments, the emissive species passively emitselectromagnetic radiation. In some embodiments, the emissive speciesdoes not emit electromagnetic radiation and may be stimulated (e.g.,triggered) to luminesce and/or reflect electromagnetic radiation thatmay be detected (e.g., in a single image produced, for example, using arolling shutter or the like).

In some embodiments, stimulation (e.g., triggering) of the speciesproduces an emission and/or changes a lifetime of the emission. In someembodiments, the lifetime of the emission identifies a characteristic ofthe species and/or the article.

In some embodiments, a characteristic of an article may be determined bydetecting a first (time-independent) steady-state photon emission by oneor more species under a first set of conditions and detecting a second(time-dependent) non-steady-state photon emission by the one or morespecies under a second set of conditions, different that the first setof conditions, wherein the change between the first emission and thesecond emission identifies a characteristic of the article.

As described above and herein, a characteristic of an emission (e.g.,the lifetime of the emission) of one or more species may be identifiedby obtaining a single image of the emission using a rolling shuttermechanism and an image sensor, such that a first portion of the imagecorresponds to a steady-state photon emission and a second portion ofthe image corresponds to a second time period after the same emissionbegins.

In some embodiments, a single pulse of electromagnetic radiation may beused to stimulate the species.

A characteristic of an emission may also be identified by exciting theemissive species by a modulated excitation, as described above. In someembodiments, advantageously, emissive species that have lifetimessubstantially faster than the modulating cycle time(s) may be used toprovide a first component of the detactable signal and those withlong-lived lifetimes that are similar to the modulating cycle times maybe used to provide a second component of the detectable signal.

In some embodiments, multiple pulses of electromagnetic radiation may beused to stimulate the species. In certain cases, multiple pulses ofelectromagnetic radiation may be useful for repeated authentication ofan article. In some embodiments, the emissive species may be stimulatedover a particular period of time such that the intensity, lifetime,and/or color of the signal produced by the image sensor in response tothe emission may be monitored over time. In some such embodiments, theemission profile of the species may be used to determine acharacteristic of an article (e.g. authenticity, freshness, whether theitem had been used, etc.) In some embodiments, a plurality of pulses ofelectromagnetic radiation of one or more chemical and/or biologicalspecies may be used to generate, for example, a complex identifiablesignal such that the time-domain of the identifiable signal correspondsto a characteristic of the article (e.g., identity, authenticity, etc.).

Generally, any stimulation that produces a detectable emission (and/orreflection) of electromagnetic radiation from a chemical and/orbiological species may be used with the systems and methods describedherein.

In some embodiments, the methods and systems described herein mayutilize a sequential release of two or more emission profiles toidentify one or more characteristics of an article.

In some cases, it may be desirable to have species that may be excitedfor months or even years. In some embodiments, electromagnetic emissionsthat occur in response to an added reactant, light, heat, radiation, ormechanochemical stimulus may be used. The availability of luminescentmaterials that are smartphone excitable enables consumers to makemeasurements without the need for additional hardware. For example,advantageously, it is possible for a consumer to test if they areinfected with a virus or if they have developed immunity to a disease bytesting for antigens and antibodies. Some applications of luminescentmaterials imaged by collecting steady-state photon emission andnon-steady-state photon emission events will make use of informationread through conventional imagery such as a bar code, QR code,photograph, identification number, company logo, or other markings. Thesmartphone excitable and readable luminescent materials augment thisconventional information and may combine, in some embodiments, to createvaluable information on the authenticity, quality, or status ofarticles, as well as determination of the presence and quantity ofbiological or chemical materials.

In some embodiments, the image sensor is positioned proximate an articlesuspected of containing a chemical and/or biological species. In someembodiments, upon excitation of the chemical and/or biological speciesto produce an emission, the image sensor may be configured to produce asingle image of the emission. In some such embodiments, the single imagemay correspond to one or more characteristics of an article.

In some embodiments, the chemical and/or biological (e.g., emissive)species may undergo a reaction (e.g., which may be detected using thesystems and methods described herein) in the presence of an analyte. Forexample, the interaction between a species (e.g., an emissive speciesand/or a chemical and/or a biological species) and an analyte mayinclude formation of a bond, such as a covalent bond (e.g.carbon-carbon, carbon-oxygen, oxygen-silicon, sulfur-sulfur,phosphorus-nitrogen, carbon-nitrogen, metal-oxygen or other covalentbonds), an ionic bond, a hydrogen bond (e.g., between hydroxyl, amine,carboxyl, thiol and/or similar functional groups, for example), a dativebond (e.g. complexation or chelation between metal ions and monodentateor multidentate ligands), and the like. The interaction may alsocomprise van der Waals interactions. In one embodiment, the interactioncomprises forming a covalent bond with an analyte. In some cases, theinteraction between the species and the analyte may comprise a reaction,such as a charge transfer reaction. In some other embodiments, thespecies may undergo a chemical or physical transformation upon a changein the surrounding environment (e.g., change in temperature) to producea determinable emission profile (e.g., pattern) from the image sensor.The determinable signal may, in some cases, persist or subside overtime.

The emissive species may also interact with an analyte via a bindingevent between pairs of biological molecules including proteins, nucleicacids, glycoproteins, carbohydrates, hormones, and the like. Specificexamples include an antibody/peptide pair, an antibody/antigen pair, anantibody fragment/antigen pair, an antibody/antigen fragment pair, anantibody fragment/antigen fragment pair, an antibody/hapten pair, anenzyme/substrate pair, an enzyme/inhibitor pair, an enzyme/cofactorpair, a protein/substrate pair, a nucleic acid/nucleic acid pair, aprotein/nucleic acid pair, a peptide/peptide pair, a protein/proteinpair, a small molecule/protein pair, a glutathione/GST pair, ananti-GFP/GFP fusion protein pair, a Myc/Max pair, a maltose/maltosebinding protein pair, a carbohydrate/protein pair, a carbohydratederivative/protein pair, a metal binding tag/metal/chelate, a peptidetag/metal ion-metal chelate pair, a peptide/NTA pair, alectin/carbohydrate pair, a receptor/hormone pair, a receptor/effectorpair, a complementary nucleic acid/nucleic acid pair, a ligand/cellsurface receptor pair, a virus/ligand pair, a Protein A/antibody pair, aProtein G/antibody pair, a Protein L/antibody pair, an Fcreceptor/antibody pair, a biotin/avidin pair, a biotin/streptavidinpair, a drug/target pair, a zinc finger/nucleic acid pair, a smallmolecule/peptide pair, a small molecule/protein pair, a smallmolecule/target pair, a carbohydrate/protein pair such as maltose/MBP(maltose binding protein), a small molecule/target pair, or a metalion/chelating agent pair. Specific non-limiting examples of speciesinclude peptides, proteins, DNA, RNA, PNA.

As used herein, an “analyte” or “chemical compound” may be any chemical,biochemical, or biological entity (e.g. a molecule) to be analyzed. Theanalyte may be in vapor phase, liquid phase, or solid phase. In someembodiments, the analyte is a vapor phase analyte. In some cases, theanalyte may be a form of electromagnetic radiation. In some cases, theanalyte may be airborne particles. In some cases, the device may beselected to have high specificity for the analyte, and may be achemical, biological, or explosives sensor, for example. In someembodiments, the analyte comprises a functional group that is capable ofinteracting with at least a portion of the device (e.g., a species). Insome cases, the device may determine changes in pH, moisture,temperature, and the like, of a surrounding medium. The analyte may be achemical species, such as an explosive (e.g., TNT), toxin, or chemicalwarfare agent. In a specific example, the analytes are chemical warfareagents (e.g., sarin gas) or analogs of chemical warfare agents (e.g.,dimethyl methylphosphonate, DMMP).

As used herein, the term “react” or “reacting” refers to the formationof a bond between two or more components to produce a stable, isolablecompound. For example, a first component and a second component mayreact to form one reaction product comprising the first component andthe second component joined by a covalent bond. The term “reacting” mayalso include the use of solvents, catalysts, bases, ligands, or othermaterials which may serve to promote the occurrence of the reactionbetween component(s). A “stable, isolable compound” refers to isolatedreaction products and does not refer to unstable intermediates ortransition states.

In some embodiments, the chemical compound (i.e. analyte) may be anaromatic species, including optionally substituted aryl species and/oroptionally substituted heteroaryl species, such as benzene, toluene,xylene, or polycyclic aromatic hydrocarbons such as benzo[a]pyrene. Insome embodiments, the analyte may be an amine-containing species such asammonia. In some embodiments, the analyte may be a nitrile-containingspecies such as acetonitrile. In some embodiments, the analyte may be anoxygen-containing species, such as a species comprising an alcohol, aketone, an ester, a carboxylate, an aldehyde, other carbonyl groups, anether, or the like. In some embodiments, the analyte may be a speciescomprising a ketone, an ester, an ether, or an aldehyde, such ascyclohexanone, ethyl acetate, THF, or hexanal. In some embodiments, theanalyte is a phosphorus-containing analyte such as DMMP. In someembodiments, the analyte may be a nitro-containing species such asnitromethane or TNT. Other examples of analytes include alcohols,olefins, nitric oxide, thiols, thioesters, and the like.

In some cases, the sensor may determine changes in a condition, or setof conditions, of a surrounding medium. As used herein, a change in a“condition” or “set of conditions” may comprise, for example, change toa particular temperature, pH, solvent, chemical reagent, type ofatmosphere (e.g., nitrogen, argon, oxygen, etc.), electromagneticradiation, or the like. In some cases, the set of conditions may includea change in the temperature of the environment in which the sensor isplaced. For example, the sensor may include a component (e.g., bindingsite) that undergoes a chemical or physical change upon a change intemperature, producing a determinable signal from the sensor.

Home tests for the presence or absence of viruses or antibodiesgenerally use controls to ensure that the tests are performed and readproperly. Such tests may provide key data used to monitor and modeloutbreaks of infectious diseases including contact tracing. In anon-limiting example, a delayed-phosphorescence material is conjugatedto an antibody and used in a lateral flow assay. Delayed-phosphorescencemay be used, for example, to eliminate background signals and createhigh-fidelity data. Specifically, detecting the luminescence in bothsteady-state and non-steady-state modes, or only in non-steady-statemode may be used to eliminate/subtract background signals, or to isolatesignals from delayed-fluorescent, prompt-phosphorescent, and/ordelayed-phosphorescent emissive materials. Although assays may beevaluated with the aid of article/structures that block stray light,detecting non-steady-state photon emission events may be also be used toselectively detect delayed-fluorescent, prompt-phosphorescent, and/ordelayed-phosphorescent emissive materials in ambient light. Thesemethods may also leverage other steady-state signals to augment themethod including information used for image alignment and calibration.

Product authentication may be accomplished, for example, using asmartphone readable tag applied to an article. In some embodiments, thetag may be designed to encode highly complex information with differentluminescent materials deposited in patterns that may be paired withoptically read codes and instructions from cloud computing resources.The ability to create complexity in the tags stems from the ability touse combinations of excited state lifetimes, wavelengths (scattered,reflected, and luminescent light), patterning, and instructions on howthe smartphone interrogates the tag. The latter may be determined byother product information (barcode or QR code) as well as location andtime data. These instructions may include the position on the article tobe analyzed, the sensitivity and exposure times used for signaldetection, and the characteristics of the light source (pulse rate,delays, or the frequency of intensity modulation). Non-limiting examplesof authentication uses include the validation of medicines, luxurygoods, and replacement parts from a manufacturer.

Smartphone excitable and readable luminescent materials may also be usedto sense the presence or absence of gases or other molecular species.Delayed-fluorescent, prompt-phosphorescent, and delayed-phosphorescentmaterials often have oxygen sensitivity, with molecular oxygen quenchingtheir emission. Quenching reduces both the lifetime and emissionintensity and combinations of parameters on the smartphone (light sourceand rolling shutter) may be configured to extract information used todetect and quantify oxygen levels. Modified atmosphere packaging isoften used to limit the oxygen exposure of products and is widely usedto maximize the shelf life of food in retail stores. Consumers andretailers may use the methods and materials presented here to verifythat the integrity of the packaging is intact. Smartphone excitable andreadable luminescent materials may also be used to detect othermolecular signatures. A number of Europium delayed-phosphorescentluminescent materials have sensitivities to water resulting in quenchingof their emission by energy transfer to the water molecules. Hence,moisture content may be monitored in packaging in this way.Additionally, there are other methods that may be used to designsmartphone excitable and readable lumiphores for the detection ofbiogenic amines indicative of spoilage and/or microbial activity, or forthe detection of sulfur compounds and carbon dioxide. All of thesemethods are relevant to packaging applications and the monitoring ofperishable articles. It is possible using multiple lumiphores todetermine one or more of these different molecular signaturessimultaneously while authenticating with a smartphone. The ability todetermine the status of the interior of a package without breaking theseal, is attractive for both consumers and retailers.

It is also possible to use smartphone excitable and readable luminescentmaterials to determine if an article has been altered. Anti-tamperingmethods may be developed that indicate when a seal has been broken.Breaking the seal may release a molecular signature that modifies thebehavior of a lumiphore. Luminescent materials may also be designed tobe sensitive to mechanical activity, cutting, resealing, heating,stretching, or any type of deformation. These may be used to detect ifthe packaging has been opened or somehow manipulated.

Smartphone excitable and readable luminescent materials may also be usedto monitor the thermal history of a material. Changes that occur as aresult of time spent at particular temperatures may be cumulative anddesigned to reveal if a material has exceeded a range that is too hot ortoo cold for a particular amount of time. Additional cumulative emissiveindicators may be designed that allow for smartphone determination ofultraviolet light or ionizing radiation exposure. These may indicatedamage or confirm treatments, for example as part of a sterilizationprotocol.

Other embodiments suitable for use in the context of some embodimentsdescribed herein are described in International Pat. Apl. Serial No.:PCT/US2009/001396, filed Mar. 4, 2009, entitled, “Devices and Methodsfor Determination of Species Including Chemical Warfare Agents”;International Pat. Apl. Serial No.: PCT/US2009/006512, filed Dec. 11,2009, entitled, “High Charge Density Structures, Including Carbon-BasedNano structures and Applications Thereof”; U.S. patent application Ser.No. 12/474,415, filed May 29, 2009, entitled, “Field Emission DevicesIncluding Nanotubes or Other Nanoscale Articles”; International Pat.Apl. Serial No.: PCT/US2011/051610, filed Oct. 6, 2010, entitled,“Method and Apparatus for Determining Radiation”; International Pat.Apl. Serial No.: PCT/US2010/055395, filed Nov. 4, 2010, entitled,“Nanostructured Devices including Analyte Detectors, and RelatedMethods”; International Pat. Apl. Serial No.: PCT/US2011/053899, filedSep. 29, 2011, entitled, “COMPOSITIONS, METHODS, AND SYSTEMS COMPRISINGPOLY(THIOPHENES); International Pat. Apl. Serial No.: PCT/US2011/025863,filed Feb. 23, 2011, entitled, “Charged Polymers and Their Uses inElectronic Devices”; and International Pat. Apl. Serial No.:PCT/US2015/039971, filed Jul. 10, 2015, entitled “FORMULATIONS FORENHANCED CHEMIRESISTIVE SENSING”, each of which are incorporated hereinin their entireties for all purposes.

In some embodiments, the emissive species(s) has been proactively addedto the article. That is to say, in some embodiments, the emissivespecies is not inherently associated with the article but is added inorder to, for example, identify a characteristic of the article. In someembodiments, a label may be associated with the article. In someembodiments, the emissive species is inherently associated with thearticle but is not present in an amount desirable for implementation ofthe invention, thus more is added for this purpose. In some embodiments,the emissive species(s) are associated with the label such that thepresence or absence of the chemical tag on the label identifies acharacteristic of the associated article.

By way of an illustrative example only, and not intending to be limitedas such, in some embodiments, one or more emissive species may beproactively added to an article that does not inherently comprise suchemissive species (or, as noted above, may comprise such compounds butthe additional of more facilitates the invention described herein). Insome embodiments, the detection by a sensor of at least one of the oneor more emissive species may identify a characteristic of the article.For example, two emissive species may be proactively added to thearticle. Detection, by a sensor, of both of the two emissive species mayindicate the authenticity of the article. By contrast, a sensor whichdetects zero or one of the two emissive species may indicate that thearticle is not authentic. Those of ordinary skill in the art wouldunderstand, based upon the teachings of this specification, that thepresence (or absence) of one or more emissive species associated withthe article may identify one or more characteristics of the article asdescribed in more detail herein (e.g., age, quality, origin, identity,etc.).

In some embodiments, a chemical tag comprises the one or more emissivespecies as described herein. In some embodiments, the chemical tagcomprises one or more, two or more, three or more, four or more, five ormore, six or more, seven or more, eight or more, nine or more or ten ormore emissive species. In some embodiments, detection of the presence(or absence), of at least one of the one or more (or two or more, etc.)emissive species in the chemical tag identifies a characteristic of thearticle. For example, in some embodiments, detection of all of theemissive species present in the chemical tag identifies thecharacteristic of the article. In some embodiments, detection of atleast a portion of the emissive species present in the chemical tagidentifies the characteristic of the article. In some embodiments, thedetection of none of the emissive species present in the chemical tagidentifies the characteristic of the article

In some embodiments, the chemical tag comprises a plurality ofidentifiable (e.g., by one or more sensors) emissive species. Asdescribed herein, in some embodiments, the chemical tag (and/or the oneor more emissive species it comprises) is not inherently associated withthe article. In some embodiments, the chemical tag may comprise one ormore emissive species inherently associated with the article, but notpresent in an amount desirable for implementation of the systems andmethods described herein, and thus more is added for this purpose. Insome embodiments, the chemical tags described herein may be useful foradditional applications. For example, in some embodiments, the chemicaltag may be associated with an ink, a preservative, a flavoring, afragrance, a colorant (e.g., a dye), and/or a structural element (e.g.,glue, tape, strapping, packaging) associated with the article (orlabel).

The chemical tags described herein may be implemented in any suitablemanner. For example, the chemical tag may be associated with a label. Insome embodiments, the chemical tag and/or label may be single use ordesigned for multiple (e.g., repeated) use.

In some embodiments, the chemical tags described herein may be combinedwith one or more additional identifying components. For example, in someembodiments, a label may comprise a chemical tag (e.g. comprising one ormore emissive species) and a second identifying component, differentthan the chemical tag. In some embodiments, a first label comprising thechemical tag and a second label comprising the identifying component mayeach be associated with an article. For example, in some embodiments,the chemical tag (or label) may be associated with a single ormultidimensional optical barcode. Those of ordinary skill in the artwould understand, based on the teachings of this specification, how toselect additional identifying components for use with the chemical tagsand systems described herein. In some embodiments, the article isassociated with a chemical tag (or label comprising the chemical tag)and a second identifying component such as an optical barcode, hologram,RFID, and/or additional chemical markers and/or biological markers.Nonlimiting examples of additional chemical markers and/or biologicalmarkers that may be used in conjunction with the systems describedherein include, but are not limited to, colorimetric dyes, fluorescentdyes, IR dyes, watermarks, nanoparticles, nanorods, quantum dots,antibodies, proteins, nucleic acids, and combinations thereof.

The term “label” as used herein is given its ordinary meaning in the artand generally refers to a component (e.g., comprising paper, fabric,plastic, ink, electronic device, or other material) associated with anarticle and giving information about said article. In an exemplaryembodiment, the label is a sticker that contains functionality. Inanother exemplary embodiment, the label is a marker. In yet anotherexemplary embodiment, the label is a stamp. In other embodiments thelabel is printed or sprayed on an article. Other labels are alsopossible and means for associating labels with an article are describedin more detail below.

The chemical tags and labels described herein may be applied to thearticle on any suitable manner. For example, in some embodiments, thechemical tag and/or label may be applied at one or more (e.g., two ormore, three or more, four or more, five or more) or at a plurality ofspatially distinct locations. For example, in some embodiments, thearticle comprises one or more (or two or more, etc.) chemical tags,wherein each chemical tag is the same or different. In some embodiments,each chemical tag may identify a same or different characteristic of thearticle.

In some embodiments, the chemical tag may be combined with one or moredifferent materials. For example, polymerizations or polymer depositionmay, in some cases, be used to form phase separation with polymers andthereby spontaneously form domains of a chemical tag or chemical tagprecursor(s) with the polymer. The polymer may be inert and the chemicaltag/chemical tag precursor may, in some cases, be released by mechanicaldisruption of the material. Alternatively, the polymer may be an activeelement and part of the triggered release, generation, or activation ofthe chemical tag. The polymer and chemical tag/chemical tag precursorand related elements may be deposited, in some cases, from solution ontoa tag or made separately and applied in a lamination step. In someembodiments, the polymer may be produced in situ to make a filmcomprising the chemical tag. Those of ordinary skill in the art wouldunderstand, based upon the teachings of this specification, that thesize and density of the chemical tag phase may be controlled by, forexample, processing conditions, surfactants and the like. Crosslinkingof the polymer host materials or the polymers encapsulants used incolloid production may be used, in some cases, to modulate the diffusionthrough these materials. Such crosslinks may be designed to be removedupon exposure to a chemical, photochemical, enzymatic, mechanical,electrochemical, or thermal process.

In some embodiments, the polymer is deformable such that deformation(e.g., stretching, bending) of the polymer releases the chemicalcompound(s) of the chemical tag.

Any suitable polymer may be used. For example, in some embodiments, thepolymer may be kinetically stable (and thermodynamically unstable) suchthat it will generally spontaneously depolymerize with a bond rupture.An example of such a class of polymers are the poly(vinyl sulfones),which, without wishing to be bound by theory, when fragmented at roomtemperature will spontaneously depolymerize. Such materials have a broadcompositional range and have generally been shown to be sensitive toradiation, base, electron transfer (redox), and thermal processes. Suchpolymers may be useful for the fabrication of polymer capsulescomprising the chemical tags, described herein. Other polymers are alsopossible and those of ordinary skill in the art would be capable ofselecting such polymers based upon the teachings of this specification.

The one or more chemical compounds may be applied to the article and/orlabel using any suitable means. Non-limiting examples of depositionmethods include spray coating, dip coating, evaporative coating, ink jetprinting, imbibing, screen printing, pad printing, gravure printing orlamination. In some embodiments, the one or more chemical compounds maybe bound to the label or article via formation of a bond, such as anionic bond, a covalent bond, a hydrogen bond, van der Waalsinteractions, and the like. The covalent bond may be, for example,carbon-carbon, carbon-oxygen, oxygen-silicon, sulfur-sulfur, phosphorus,nitrogen, carbon-nitrogen, metal-oxygen, or other covalent bonds. Thehydrogen bond may be, for example, between hydroxyl, amine, carboxyl,thiol, and/or similar functional groups.

In some embodiments, the chemical tag and/or label are edible. That isto say, in some embodiments, the chemical tag and/or label may be safelyconsumed by a subject (e.g., a human, an animal). Non-limiting examplesof chemical compounds that may be used in the chemical tag (or label)include compounds listed in the Sigma-Aldrich Ingredients Catalog:Flavors & Fragrances (2014) and Sigma-Aldrich and the Sigma-AldrichFlavor & Fragrance Ingredients Supplement (2018), each of which areincorporated by reference in its entirety for all purposes.

In some embodiments, the chemical tag includes porous luminescentsilicon (e.g., which, in some cases, may transform to silicon dioxideover time and therefore generally be considered harmless under somecircumstances).

The labels described herein may comprise any suitable substrate forcontaining or otherwise associating the chemical tag with the article.For example, in some embodiments, the label may comprise a substrate,and a chemical tag (e.g. comprising one or more chemical compounds)associated with the substrate. Non-limiting examples of suitablesubstrates include silicone, silica, glass, metals, microporousmaterials, nanoporous materials, polymers, gels, and natural materials(e.g., paper, wood, rocks, tissues, hair, fur, leather).

In some embodiments, the label comprises a means for attaching the labelto an article. Non-limiting examples of suitable means for attaching thelabel include adhesives, lamination, melt bonding, spray coating, spincoating, printing, strapping, and combinations thereof.

Any suitable type of sensor may be used to detect the presence (orabsence) of a chemical tag (or one or more emissive species the chemicaltag comprises). The sensor may comprise one or more components capableof detecting changes in optical properties such as wavelength,intensity, color, fluorescence, light scattering, or other features.Those of ordinary skill in the art would be capable of selectingsuitable sensors based upon the teachings of this specification.

In some embodiments, the sensor is positioned proximate an articlesuspected of containing a chemical tag. In some embodiments, upondetection of the compound(s), the sensor may be configured to send asignal. In some such embodiments, the signal may correspond to one ormore characteristics of the article (e.g., temporal thermal history). Asdescribed herein, in some embodiments, the chemical tag (or the one ormore chemical compounds the chemical tag comprises) are not inherent tothe article. For example, in some embodiments, a sensor will not detectthe presence (e.g., amount, concentration, non-zero rate of release) ofa chemical compound adjacent an article unless the chemical compound hadbeen proactively associated with the article prior to sensing.

In an exemplary set of embodiments, an imaging device comprises a sourceof electromagnetic radiation configured to emit radiation to excitenon-steady-state emission in emissive species during emission timeperiods of the emissive species, the emission time periods being atleast 10 nanoseconds; an electromagnetic radiation sensor comprising aplurality of photodetectors arranged in an array of rows and columns,wherein the electromagnetic radiation sensor is configured to sense thenon-steady-state emission from the emissive species during the emissiontime period; and processing circuitry configured to: sequentially readout rows or columns of the array to provide a plurality of time-encodedsignals; and identify a characteristic of the emissive species based ona comparison of at least two of the plurality of time-encoded signals.

In some embodiments, the emissive time periods are at least 100nanoseconds. In some embodiments, the emissive time periods are at least1 microsecond.

In an exemplary set of embodiments, an imaging device comprises a sourceof electromagnetic radiation configured to emit radiation to excitenon-steady-state emission in emissive species during emission timeperiods of the emissive species, the emission time periods being atleast 10 nanoseconds; an electromagnetic radiation sensor, wherein theelectromagnetic radiation sensor is configured to sense thenon-steady-state emission from the emissive species during the emissiontime period; and processing circuitry configured to: globally exposeand/or read data from the electromagnetic radiation sensor to provide aplurality of time-encoded signals and identify a characteristic of theemissive species based on a comparison of two or more of the pluralityof time-encoded signals.

In some embodiments, the processing circuitry is further configured togenerate one or more images based on the plurality of time-encodedsignals, and wherein identifying the characteristic of the emissivespecies is based on the one or more images.

In some embodiments, the processing circuitry is further configured to:generate a first portion of an image based on time-encoded signals forone or more first rows or one or more first columns of the array;generate a second portion of the image based on time-encoded signals forone or more second rows or one or more second columns of the array, andwherein identifying the characteristic of the emissive species is basedon a comparison of the first portion of the image and the second portionof the image.

In an exemplary set of embodiments, a system configured foridentification of a characteristic of a chemical tag, comprises achemical tag associated with an article, wherein the chemical tagcomprises an emissive species, wherein the emissive species produces adetectable non-steady-state emission during an emission time periodunder a set of conditions, and wherein the emission time period is atleast 10 nanoseconds; an excitation component configured to excite theemissive species under the set of conditions such that the detectablenon-steady-state emission, which varies over the image capture timeperiod, is produced; an image sensor configured to detect the detectablenon-steady-state emission; and an electronic hardware componentconfigured to convert the detected non-steady state emission into asingle image, wherein the single image comprises a first portioncorresponding to a first portion of the emission time period and asecond portion corresponding to a second portion of the emission timeperiod, and wherein a difference between a property of the first portionand the second portion is associated with a characteristic of thechemical tag.

In some embodiments, at least one characteristic of the detectablenon-steady state emission varies during detection of the detectablenon-steady state emission by an image sensor. In some embodiments, theemissive species is a chemical and/or biological species. In someembodiments, the chemical tag comprises a plurality of emissive species.In some embodiments, the excitation component is configured to excite aplurality of emissive species. In some embodiments, at least twoemissive species of the plurality of emissive species are chemicaland/or biological species. In some embodiments, the excitation componentcomprises a source of electromagnetic radiation. In some embodiments,the source of electromagnetic radiation is configured to emitsubstantially white light. In some embodiments, the source ofelectromagnetic radiation comprises an LED, an OLED, a fluorescentlight, and/or an incandescent bulb. In some embodiments, the source ofelectromagnetic radiation comprises a flash lamp.

In some embodiments, the excitation component comprises an opticalshutter, a light valve, an optical modulator, a dynamic refractorymaterial, a rotating element that periodically blocks theelectromagnetic radiation, and/or a moving mirror. In some embodiments,the excitation component is configured to excite the emissive species byelectrical, mechanical, chemical, particle, or thermal stimulation. Insome embodiments, the excitation component and the image sensor areintegrated in a single component. In some embodiments, the excitationcomponent and the image sensor are separate. In some embodiments, theimage sensor comprises a CMOS sensor, charge coupled device, orphotodiode. In some embodiments, the image sensor is associated with arolling shutter mechanism. In some embodiments, the image sensor isassociated with a global shutter. In some embodiments, the image sensoris incorporated in a smartphone. In some embodiments, the emissivespecies comprises one or more thermally activated delayed fluorescence(TADF) molecules or molecular complexes. In some embodiments, theemissive species comprises an inorganic phosphor. In some embodiments,the emissive species comprises bromine, iodine, sulfur, selenium,telluride, phosphorus, tin, lead, mercury, and/or cadmium. In someembodiments, the emissive species comprises bismuth, rhenium, iridium,platinum, gold, or copper. In some embodiments, the emissive speciescomprises a lanthanide or actinide. In some embodiments, the emissivespecies is associated with a pill, a capsule, or packaging of a product.In some embodiments, the article comprises a coating, wherein thecoating comprises the emissive species. In some embodiments, thecharacteristic of the article and/or chemical tag is associated with thepresence of a chemical agent, biological agent, explosive, toxicchemical, heavy metal, narcotic, xenobiotic, and/or radiation source. Insome embodiments, the characteristic of the article is an authenticityof the article. In some embodiments, the system comprises a secondchemical tag. In some embodiments, the system comprises a secondidentifiable component. In some embodiments, the second identifiablecomponent comprises an optical barcode, hologram, watermark, RFID,invisible ink, dyes, colorimetric markers, fluorescent markers,nanoparticles, nanorods, quantum dots, antibodies, proteins, nucleicacids, or combinations thereof. In some embodiments, the emissivespecies is associated with a point-of-care, field, or home diagnostickit or method. In some embodiments, one or more components are inwireless communication with a component providing instructions forexcitation of the emissive species and/or detection of the detectableemission.

In an exemplary set of embodiments, a method for identifying a change inan emissive species over a period of time, comprises exciting thespecies such that it produces a detectable non-steady-state emissionduring an emission time period, wherein the emission time period is atleast 10 nanoseconds; obtaining, using an image sensor, data associatedwith the detectable non-steady state emission; optionally, create, basedon at least a portion of the data obtained using the image sensor, asingle image, wherein a first set of data used to create a first portionof the single image corresponds to a first portion of the emission timeperiod, and wherein a second set of data used to create a second portionof the single image corresponds to a second portion of the emission timeperiod; and determining, based upon a difference between the firstportion and the second portion of the single image, the change in theemissive species.

In an exemplary set of embodiments, a method for identifying a change inan emissive species over a period of time, comprises causing the speciesto emit non-steady-state electromagnetic radiation during an emissiontime period; obtaining, using an image sensor, a single image of atleast a portion of the electromagnetic radiation emitted by the emissivespecies; identifying information from a first image portioncorresponding to emission of electromagnetic radiation by the emissivespecies at least at a first point in time; identifying information froma second image portion corresponding to emission of electromagneticradiation by the emissive species at least at a second point in time;and determining, from at least the information from the first imageportion and the information from the second image portion, the change inthe emissive species.

In some embodiments, the method comprises identifying information frommore than two image portions of the single image corresponding toemission of electromagnetic radiation by the emissive species at morethan two points in time, and/or obtaining a plurality of images, eachimage being of at least a portion of the electromagnetic radiationemitted by the emissive species, and for each image identifyinginformation from a first image portion corresponding to emission ofelectromagnetic radiation by the emissive species at least at a firstpoint in time, and identifying information from a second image portioncorresponding to emission of electromagnetic radiation by the emissivespecies at least at a second point in time; and from informationidentified from the more than two image portions, and/or frominformation from the plurality of images, determining a change in theemissive species.

In some embodiments, the emission time period is at least 10nanoseconds. In some embodiments, exciting the species comprisesexposing the species to electromagnetic radiation. In some embodiments,the exciting electromagnetic radiation is provided as a single pulse, aperiodic pulse, a sequence of pulses, a pulse of continuously varyingintensity, or any combination thereof. In some embodiments, theelectromagnetic radiation is modulated by an electrical signal, shutter,refractory material, optical modulator, moving mirror, mechanicaldevice, or light valve. In some embodiments, the electromagneticradiation comprises visible light. In some embodiments, theelectromagnetic radiation comprises substantially white light. In someembodiments, the electromagnetic radiation comprises discrete wavelengthranges. In some embodiments, exciting the species comprises exposing thespecies to pulsed and/or modulated light from an LED, an OLED, afluorescent light, and/or an incandescent bulb. In some embodiments,exciting the species comprises exposing the species to a flash lamp. Insome embodiments, exciting the species comprises applying a voltage,ionizing radiation, a physical force, or chemical reaction. In someembodiments, the species is associated with a packaging component.

In some embodiments, the species undergoes a chemical and/or biologicalreaction upon excitation. In some embodiments, exposure to an analytecauses a change in one or more of an intensity of the emitted light, apolarization of the emitted light, a spatial profile of the emittedlight or a change in the emission lifetime of the emissive species.

In some embodiments, the method further comprises a second step ofactivating an article. In some embodiments, the second step ofactivating an article causes a change in emission lifetime, spatialprofile, polarization, chemical sensitivity, intensity and/or blockageof the first step of exciting the species. In some embodiments, thesecond step of exciting the species produces generation of a colorand/or change in absorption and/or emission. In some embodiments,combinations of different first, second and additional steps of excitingthe species cause changes in the images that are acquired over thecourse of 100 nanoseconds to 100 milliseconds.

In an exemplary set of embodiments, a system comprises a radiationsource configured to generate electromagnetic radiation for exciting anemissive species such that the emissive species produces a detectablenon-steady-state emission during an emission time period, the emissiontime period being at least 10 nanoseconds; a sensor configured to:detect, during a first portion of the emission time period, a firstemission from the emissive species, and detect, during a second portionof the emission time period, a second emission from the emissivespecies; and processing circuitry configured to identify acharacteristic of the emissive species based on a difference between aproperty of the first emission detected during the first portion of theemission time period and a property of the second emission detectedduring the second portion of the emission time period.

In some embodiments, the radiation source is configured to generateelectromagnetic radiation for exciting a second emissive species suchthat the second emissive species produces a second detectablenon-steady-state emission during a second emission time period, thesecond emission time period being at least 10 nanoseconds. In someembodiments, the sensor is configured to detect, during a first portionof the second emission time period, a first emission from the secondemissive species, and to detect, during a second portion of the secondemission time period, a second emission from the second emissivespecies. In some embodiments, each emissive species comprises the sameemitter. In some embodiments, each emissive species comprises aplurality of emitters. In some embodiments, the emission time period isless than 100 milliseconds, less than 50 milliseconds, less than 5microseconds, less than 1 microsecond, or less than 0.1 microseconds.

In some embodiments, the system further comprises an article associatedwith the emissive species, wherein the characteristic of the emissivespecies corresponds to a characteristic of the article. In someembodiments, the characteristic of the emissive species corresponds tothe presence or absence of an analyte. In some embodiments, thecharacteristic corresponds to exposure of the emissive species totemperature, thermal history, pH, UV radiation, humidity, asterilization technique(s), a chemical(s), a pathogen(s), a biologicalspecies, and/or mechanical stress.

In an exemplary set of embodiments, a system comprises a radiationsource configured to generate electromagnetic radiation for exciting anemissive species such that the emissive species produces a detectablenon-steady-state emission during an emission time period; anelectromagnetic radiation sensor configured to sense during a singleexposure: first emission from the emissive species during a firstportion of the emission time period, and second emission from theemissive species during a second portion of the emission time period,wherein the emission time period is at least 10 nanoseconds and is lessthan a duration of the single exposure; and processing circuitryconfigured to identify a characteristic of the emissive species based ona difference between a property of the first emissions detected duringthe first portion of the emission time period and a property of thesecond emissions detected during the second portion of the emission timeperiod.

In an exemplary set of embodiments, a method for identifying acharacteristic of an emissive species, comprises generatingelectromagnetic radiation; exciting, using the electromagneticradiation, an emissive species such that the emissive species produces adetectable non-steady-state emission during an emission time period, theemission time period being at least 10 nanoseconds; detecting, during afirst portion of the emission time period, a first emission from theemissive species, and detecting, during a second portion of the emissiontime period, a second emission from the emissive species; andidentifying the characteristic of the emissive species based on adifference between a property of the first emission detected during thefirst portion of the emission time period and a property of the secondemission detected during the second portion of the emission time period.

In some embodiments, detecting the first emission comprises exposing anelectromagnetic radiation sensor to the detectable non-steady-stateemission, the electromagnetic radiation sensor comprising a plurality ofphotodetectors arranged in an array of rows and columns. In someembodiments, the method comprises sequentially reading out rows orcolumns of the array to provide a plurality of time-encoded signals,wherein a first time-encoded signal corresponds to the first emissionand to a second time-encoded signal corresponds to the second emission.In some embodiments, the step of identifying a characteristic of theemissive species comprises comparing the first and second time-encodedsignals.

In an exemplary set of embodiments, a method for identifying acharacteristic of an emissive species, comprises exciting the speciessuch that the species produces a detectable emission during an emissiontime period, wherein the emission time period is at least 10nanoseconds; obtaining, using an image sensor, a first image of thedetectable emission, wherein a first portion of the first imagecorresponds to a first portion of the emission time period, and whereina second portion of the first image corresponds to a second portion ofthe emission time period; and determining, based upon a differencebetween the first portion and the second portion of the first image, thecharacteristic of the species.

In some embodiments, exciting the species comprises exposing the speciesto electromagnetic radiation. In some embodiments, excitingelectromagnetic radiation is provided as a single pulse, a periodicpulse, a sequence of pulses, a pulse of continuously varying intensity,or any combination thereof. In some embodiments, the electromagneticradiation is modulated by an electrical signal, shutter, refractorymaterial, optical modulator, moving mirror, mechanical device, or lightvalve. In some embodiments, the electromagnetic radiation comprisesvisible light. In some embodiments, the electromagnetic radiationcomprises substantially white light. In some embodiments, theelectromagnetic radiation comprises discrete wavelength ranges. In someembodiments, exciting the species comprises exposing the species topulsed and/or modulated light from an LED, an OLED, a fluorescent light,and/or an incandescent bulb. In some embodiments, exciting the speciescomprises exposing the species to a flash lamp. In some embodiments,exciting the species comprises applying a voltage, ionizing radiation, aphysical force, or chemical reaction.

In some embodiments, the species is associated with a packagingcomponent. In some embodiments, the species undergoes a chemical and/orbiological reaction upon excitation. In some embodiments, exposure to ananalyte causes a change in the emitted light intensity, polarization,spatial profile, and/or a change in the emission lifetime of theemissive species. In some embodiments, the method further comprises asecond step of activating an article. In some embodiments, the secondstep of activating an article causes a change in emission lifetime,spatial profile, polarization, chemical sensitivity, intensity and/orblockage of the first step of exciting the species. In some embodiments,the second step of exciting the species produces generation of a colorand/or change in absorption and/or emission. In some embodiments,combinations of different first, second and additional steps of excitingthe species cause changes in the images that are acquired over thecourse of 100 nanoseconds to 100 milliseconds.

In an exemplary set of embodiments, a method for identifying acharacteristic of an article comprises: positioning an image sensorproximate an article suspected of containing an emissive tag;stimulating the article such that the emissive tag, if present, producesa detectable non-steady-state emission; obtaining, using the imagesensor, a single image of the detectable non-steady-state emission,wherein a first portion of the single image corresponds to a first timeperiod after stimulating the analyte, and wherein a second portion ofthe single image corresponds to a second time period after stimulatingthe analyte, different than the first time period; and determining,based upon a difference between the first portion and the second portionof the single image, the characteristic of the article.

In an exemplary set of embodiments, a system comprises a radiationsource configured to generate electromagnetic radiation for exciting anemissive species such that the emissive species produces a detectablenon-steady-state emission during an emission time period; anelectromagnetic radiation sensor including a plurality of photodetectorsconfigured to detect the non-steady state emission during the emissiontime period; a controller configured to control a timing of generationof the electromagnetic radiation by the radiation source such thatpulsed or frequency modulated intensity electromagnetic radiation isgenerated during the capture of the one or more images; and processingcircuitry configured to: generate, based on output of the plurality ofphotodetectors, one or more images, the emission time period being lessthan a time to capture a single image of the one or more images; and foreach of the one or more images, determine a first property of a firstportion of the image and a second property of a second portion of theimage, and identify a characteristic of the emissive species based, atleast in part, on the first property and the second property.

In some embodiments, the radiation source is configured to generateelectromagnetic radiation for exciting a second emissive species suchthat the second emissive species produces a second detectablenon-steady-state emission during a second emission time period, thesecond emission time period being at least 10 nanoseconds. In someembodiments, the sensor is configured to detect, during a first portionof the second emission time period, a first emission from the secondemissive species, and to detect, during a second portion of the secondemission time period, a second emission from the second emissivespecies. In some embodiments, each emissive species comprises the sameemitter. In some embodiments, each emissive species comprises aplurality of emitters.

In some embodiments, the electromagnetic radiation sensor is configuredto capture a plurality of images, and wherein the processing circuitryis further configured to: determine an average of the first propertyover the plurality of images; determine an average of the secondproperty over the plurality of images; and identify a characteristic ofthe emissive species based, at least in part, on the average of thefirst property and the average of the second property. In someembodiments, a delayed emission can be detected in the same image withnormal reflected light. In some embodiments, excitation is performed bypulsed light and/or frequency modulated light intensity. In someembodiments, the electromagnetic radiation sensor is configured tocapture a plurality of images, and wherein the controller is furtherconfigured to control the radiation source to generate a pulse orintensity modulated at different frequencies of electromagneticradiation prior to capture of each of the plurality of images.

In some embodiments, the plurality of photodetectors are arranged in anarray of rows and columns, and wherein the processing circuitry isfurther configured to: sequentially read out rows or columns of thearray to provide a plurality of time-encoded signals; and generate theone or more images based on the plurality of time-encoded signals. Insome embodiments, the plurality of photodetectors are contained within asingle integrated electronic chip. In some embodiments, the plurality ofphotodetectors are contained in multiple integrated electronic chips.

In an exemplary set of embodiments, a system comprises an excitationcomponent configured to excite an emissive species such that theemissive species produces a detectable non-steady-state emission duringan emission time period, wherein the emission time period is at least 10nanoseconds; an image sensor configured to detect at least a portion ofthe detectable non-steady-state emission; and an electronic hardwarecomponent configured to produce a single image comprising a firstportion corresponding to a first portion of the emission time period anda second portion corresponding to a second portion of the emission timeperiod.

In some embodiments, the single image further comprises a third portioncorresponding to a third portion of the emission time period. In someembodiments, the single image further comprises subsequent portionscorresponding to multiple other portions of the emission time period. Insome embodiments, the first portion of the emission time period isdifferent from the second portion of the emission time period. In someembodiments, the first portion of the emission time period at leastpartially overlaps with the second portion of the emission time period.

In an exemplary set of embodiments, a system comprises an excitationcomponent configured to expose an emissive species to non-steady-stateelectromagnetic radiation, an image sensor configured to detect at leasta portion of electromagnetic radiation emitted by the emissive species,and an electronic hardware component configured to produce a singleimage comprising at least a first image portion corresponding toemission of electromagnetic radiation by the emissive species at leastat a first point in time, and a second image portion corresponding toemission of electromagnetic radiation by the emissive species at leastat a second point in time. In some embodiments, the electronic hardwarecomponent is configured to produce the single image comprising more thantwo image portions corresponding to emission of electromagneticradiation by the emissive species at more than two respective points intime, and/or produce multiple images each comprising at least a firstimage portion corresponding to emission of electromagnetic radiation bythe emissive species at least at a first point in time, and second imageportion corresponding to emission of electromagnetic radiation by theemissive species at least at a second point in time.

In an exemplary set of embodiments, a system configured foridentification of a characteristic of an article comprises a chemicaltag associated with the article, wherein the chemical tag comprises anemissive species, wherein the emissive species produces a detectablenon-steady-state emission during an emission time period under a set ofconditions, and wherein the emission time period is at least 10nanoseconds, an excitation component configured to excite the emissivespecies under the set of conditions such that the detectablenon-steady-state emission, which varies over the image capture timeperiod, is produced, an image sensor configured to detect the detectablenon-steady-state emission, and an electronic hardware componentconfigured to convert the detectable emission into a single image,wherein the single image comprises a first portion corresponding to afirst portion of the emission time period and a second portioncorresponding to a second portion of the emission time period, andwherein a difference between a property of the first portion and thesecond portion is associated with a characteristic of the article. Insome embodiments, the single image further comprises subsequent portionscorresponding to multiple other portions of the emission time period.

In an exemplary set of embodiments, a method for detecting the presenceof a stimulus, comprises exposing an article comprising a chemical tagto a set of conditions comprising the stimulus, wherein the chemical tagundergoes a chemical and/or biological reaction in the presence of thestimulus that changes the lifetime, wavelength, and/or intensity of oneor more emissive species in the tag, positioning an image sensorproximate the article, obtaining, using the image sensor, a single imageof a portion of the article comprising the chemical tag, wherein a firstportion of the single image corresponds to a first time period afterexposing the article, and wherein a second portion of the single imagecorresponds to a second time period after exposing the article,different than the first time period, and determining, based upon adifference between the first portion and the second portion of thesingle image, the characteristic of the article.

In some embodiments, the method further comprises obtaining a secondimage of at least a portion of the detectable emission, wherein thesecond image is obtained at a different excitation method, position,angle, distance, and/or orientation than the first image. In someembodiments, the method further comprises determining, based upon adifference between the first image and the second image, thecharacteristic of the species.

In some embodiments, the chemical tag undergoes a chemical and/orbiological reaction upon stimulating the article. In some embodiments,stimulating the article comprises producing a chemical and/or biologicalreaction in the chemical tag. In some embodiments, the chemical tagcomprises at least one emissive dye having an excited state lifetimemore than 10 nanoseconds. In some embodiments, the image sensor isassociated with a rolling shutter mechanism. In some embodiments, theimage sensor is associated with a global shutter. In some embodiments,the chemical tag produces a detectable emission having an excited statelifetime more than 10 nanoseconds in the presence of the stimulus. Insome embodiments, a second stimulation of the article causes a processthat changes the characteristics of the chemical tag by causing partialblockage of the excitation, quenching of one or more emissive species,changes in the physical properties of the matrix, activation of a newemissive species, and/or a change in the emissive characteristics of oneof more emissive species. In some embodiments, the second stimulation isused to detect that an article has been previously subjected to an imagesensor. In some embodiments, the second stimulation is used to produce achange in the tag that will change the optical image read in subsequentimage sensors.

In an exemplary set of embodiments, a composition comprises an emissivespecies configured to be associated with an article, wherein excitationof the emissive species produces a detectable signal having one or moredelayed emissions of greater than or equal to 10 nanoseconds, andwherein the detectable signal corresponds to a temporal thermal historyof the article.

In an exemplary set of embodiments, a label, comprises a first emissivespecies optionally having one or more first detectable delayedemission(s) of greater than or equal to 10 nanoseconds corresponding toa first temporal thermal history of the first emissive species, andoptionally a second emissive species having one or more seconddetectable delayed emission(s) of greater than or equal to 10nanoseconds corresponding to a second temporal thermal history of thesecond emissive species, different than the first temporal thermalhistory, wherein the first detectable delayed emission, if present uponexcitation of the first emissive species, corresponds to identificationof the first emissive species being exposed to the first temporalthermal history and the second detectable delayed emission, ifdetectable, corresponds to identification of the second emissive speciesbeing exposed to the second temporal thermal history.

In some embodiments, the label is configured to be proactively added toan article, such that the label provides a temporal thermal profile ofthe article.

In an exemplary set of embodiments, a method comprises exciting one ormore emissive species associated with an article, and detecting, using adetector, a detectable delayed emission of the emissive species, whereinthe detectable delayed emission, if present, has a delayed emission ofgreater than or equal to 10 nanoseconds, and wherein the detectabledelayed emission, if present, corresponds to an exposure of the articleto a temporal thermal history.

In an exemplary set of embodiments, a method comprises exciting one ormore first emissive species, optionally, exciting one or more secondemissive species, detecting, using a detector, a first detectabledelayed emission(s) produced by the first emissive species and/or asecond detectable delayed emission(s) produced by the second emissivespecies, wherein, the first detectable delayed emission, if present,corresponds to exposure of the first emissive species to a firsttemperature, and wherein, the second detectable delayed emission, ifpresent, corresponds to exposure of the second emissive species to asecond temperature, different than the first temperature, wherein, atleast one detectable delayed emission is present.

In an exemplary set of embodiments, a system comprises an excitationcomponent configured to excite, using electromagnetic radiation, anemissive species such that, if single or multiple emissive species, ortheir precursors, were exposed to a temporal thermal history, produces adetectable delayed emission of greater than or equal to 10 nanoseconds,and a detector configured to detect at least a portion of the detectabledelayed emission.

In some embodiments, detecting comprises a rolling shutter mechanism. Insome embodiments, detecting comprises a global shutter. In someembodiments, the detectable delayed emission comprises a peak intensity,emission lifetime, absorption wavelength, and/or emission wavelength. Insome embodiments, the response involves a change in the wavelength ofthe absorption or emission related to the delayed emission. In someembodiments, the response involves a change in intensity of a detectablesignal. In some embodiments, the response involves a change in thedelayed emission lifetime. In some embodiments, the response involvesthe creation of a new delayed emission. In some embodiments, theresponse involves the removal of a delayed emission. In someembodiments, the response involves two components combining to produceor remove a delayed emission.

In some embodiments, the label is produced by the deposition of secondmaterial onto a delayed emission material in order to produce a systemcapable of displaying a temporal thermal history. In some embodiments,the response involves a matrix that changes its physical properties tocreate changes in the delayed emission signal. In some embodiments, theresponse involves the diffusion of one or more materials to createchanges in the delayed emission signal. In some embodiments, theresponse involves a matrix that undergoes a phase change that producesthe delayed emission signal. In some embodiments, the response involveschemical reaction to produce the delayed emission signal. In someembodiments, the response involves changes in aggregation to produce thedelayed emission signal. In some embodiments, the response is producedby an enhancement in energy transfer from an antenna molecule or polymerto a delayed emission component. In some embodiments, the responseproduces a pattern from the delayed emission signal. In someembodiments, the response is produced from materials that are safe forhumans consume. In some embodiments, the response wherein thecomposition is produced with components proximate to each other. In someembodiments, one of the components is fused onto or into glass. In someembodiments, is produced with components separated physically from eachother. In some embodiments, is produced by spray deposition, ink jetprinting, printing, or lamination.

In some embodiments, the delayed emission has a lifetime greater than 10nanoseconds, greater than 100 nanoseconds, greater than 1 microsecond,greater than 100 microseconds, or greater than 1 millisecond.

In some embodiments, the delayed emission species contains a metal ion,is an organic molecule, is a nanoparticle, or is an organic moleculecontaining heavy atoms.

In some embodiments, the detector is a smartphone component.

In some embodiments, excitation of the emissive species is accomplishedby a light source with modulated intensity at different frequencies. Insome embodiments, excitation of the emissive species is accomplished bya light flash or a laser pulse. In some embodiments, the reader is astreak camera. In some embodiments, the reader is a device capable ofselectively detecting a delayed emission. In some embodiments, thereader is a device capable of selectively detecting a delayed emissionin a complex environment with non-delayed emission, ambient, andreflected light present. In some embodiments, the reader is a devicecapable of selectively detecting a delayed emission and is also capableof detecting fluorescence, ambient, and reflected light. In someembodiments, the reader is capable of detecting patterns of delayedemission to produce information about a thermal or cold exposure. Insome embodiments, the reader is capable of detecting patterns of delayedemission as well as patterns from reflected, ambient, or non-delayedemission to produce information about a thermal or cold exposure. Insome embodiments, the reader is capable of integrating information of athermal or cold exposure with other information optically encoded on theproduct. In some embodiments, the reader contains a CMOS imaging chip.In some embodiments, the reader uses the rolling shutter effect tocollect the delayed emission data.

In an exemplary set of embodiments, a method comprises determining anidentity or characteristic of a chemical/biological species bycombining: a first electromagnetic radiation signal comprising at leasta steady-state photon emission event, and a second electromagneticradiation signal comprising at least a non-steady-state photon emissionevent.

In an exemplary set of embodiments, a method comprises determining anidentity or characteristic of a chemical/biological species bycombining: a first electromagnetic radiation signal and a secondelectromagnetic radiation signal, wherein the first electromagneticsignal comprises at least a first photon emission event occurring within10 nanoseconds of an excitation event that caused the first photonemission event, and a second electromagnetic signal comprising at leasta second photon emission event occurring after 10 nanoseconds of theexcitation event that caused the second photon emission event.

In some embodiments, the first photon emission event comprises anemission produced by an emissive species having an excited statelifetime of less than or equal to 10 nanoseconds. In some embodiments,the second photon emission event comprises an emission produced by anemissive species having an excited state lifetime of at least 10nanoseconds.

In an exemplary set of embodiments, a method of reading a biologicaldiagnostic assay wherein an imaging device provides a readout from theassay comprises detecting two or more signals emanating from the assay,wherein each of the two or more signals are selected from a subtractivecolor, reflected color, chemiluminescence, prompt-fluorescence,delayed-fluorescence, prompt-phosphorescence, anddelayed-phosphorescence emission.

In some embodiments, each signal is read using a smartphone or digitalcamera.

In an exemplary set of embodiments, a system comprises an excitationcomponent configured to excite a first emissive species such that thefirst emissive species produces a detectable steady-state photonemission signal, the excitation component is configured to excite asecond emissive species such that the second emissive species produces adetectable non-steady-state photon emission signal, and a sensorconfigured to detect at least a portion of the detectable steady-statephoton emission signal and at least a portion of the detectablenon-steady-state emission signal.

In some embodiments, the system further comprises an electronic hardwarecomponent configured to combine the detectable steady-state emission andthe detectable non-steady-state emission into a determinable signal. Insome embodiments, the detectable steady-state emission and/or thedetectable non-steady-state emission correspond to a characteristic ofthe first emissive species and/or the second emissive species.

In some embodiments, the signal corresponds to a quantity of a targetbiological species. In some embodiments, at least one emission isselected from the group consisting of subtractive color, reflectedcolor, chemiluminescence, prompt-fluorescence, delayed-fluorescence,prompt-phosphorescence, or delayed-phosphorescence. In some embodiments,the first electromagnetic radiation signal is a colorimetric signal andthe second electromagnetic radiation signal is a prompt-fluorescencesignal. In some embodiments, the first electromagnetic radiation signalis a colorimetric signal and the second electromagnetic radiation signalis a delayed-fluorescence signal. In some embodiments, the firstelectromagnetic radiation signal is a colorimetric signal and the secondelectromagnetic radiation signal is a prompt-phosphorescence signal. Insome embodiments, the first electromagnetic radiation signal is acolorimetric signal and the second electromagnetic radiation signal is adelayed-phosphorescence signal. In some embodiments, the firstelectromagnetic radiation signal is a colorimetric signal and the secondelectromagnetic radiation signal is a chemiluminescence signal. In someembodiments, the first electromagnetic radiation signal is aprompt-fluorescence signal and the second electromagnetic radiationsignal is a delayed-phosphorescence signal. In some embodiments, atleast one signal is collected in a steady-state mode and at least oneother signal is collected using a time synchronized light source. Insome embodiments, at least one signal is collected when a timesynchronized electromagnetic radiation source is off and at leastanother signal is collected when a time synchronized electromagneticradiation source is on. In some embodiments, at least one signal iscollected while the assay is illuminated by one or more LED lightsources. In some embodiments, the excitation event is a source ofelectromagnetic radiation. In some embodiments, the source ofelectromagnetic radiation comprises a flash from a smartphone or digitalcamera.

In some embodiments, the system or method further comprises a biologicaldiagnostic assay associated with the first electromagnetic radiationsignal and/or second electromagnetic radiation signal. In someembodiments, the biological diagnostic assay is a lateral flow assay. Insome embodiments, the biological diagnostic assay is a loop-mediatedisothermal amplification (LAMP) for nucleic acid detection. In someembodiments, the delayed-phosphorescence is associated with a europiumor terbium complex. In some embodiments, nanoparticles are used toprovide a colorimetric signal. In some embodiments, nanoparticles areused to provide an emissive signal. In some embodiments, changes inlocal environment and/or a biomolecular recognition event changes atleast one signal.

In some embodiments, a rolling shutter mechanism is associated with themethod or system.

In an exemplary set of embodiments, a system comprises a radiationsource configured to emit radiation having one or more wavelengthswithin an electromagnetic radiation spectrum, and an emissive species,wherein a first portion of the electromagnetic radiation spectrumcomprises radiation having a wavelength between 425 nm and 475 nm,wherein a second portion of the electromagnetic radiation spectrumcomprises radiation having a wavelength between 525 nm and 725 nm, andwherein the radiation source is configured to produce a wavelength ofelectromagnetic radiation that interacts with the emissive species suchthat the emissive species produces a detectable signal having one ormore delayed emissions of greater than or equal to 10 nanoseconds.

In an exemplary set of embodiments, a system comprises a source ofelectromagnetic radiation having a plurality of wavelengths, and anemissive species, wherein the emissive species is configured to producea detectable signal having one or more delayed emissions of greater thanor equal to 10 nanoseconds, and wherein the plurality of wavelengthsspans a wavelength range greater than or equal to 50 nm.

In some embodiments, the electromagnetic radiation produced by thesource is unadulterated prior to exposure to the emissive species. Insome embodiments, the system does not comprise a light filter positionedbetween the source and the emissive species. In some embodiments, thesource is a component of a consumer electronic device. In someembodiments, the consumer electronic device is a smartphone, tablet,computer, digital camera, or the like.

In an exemplary set of embodiments, a system comprises an excitationcomponent configured to produce a plurality of wavelengths ofelectromagnetic radiation, wherein: the excitation component isconfigured to excite a first emissive species such that the firstemissive species produces a detectable stead-state photon emissionsignal, the excitation component is configured to excite a secondemissive species such that the second emissive species produces adetectable non-steady-state photon emission signal, and a sensorconfigured to detect at least a portion of the detectable steady-statephoton emission signal and at least a portion of the detectablenon-steady-state emission signal.

In an exemplary set of embodiments, a system comprises a radiationsource configured to generate a plurality of wavelengths ofelectromagnetic radiation for exciting an emissive species such that theemissive species produces a detectable non-steady-state emission duringan emission time period, the emission time period being at least 10nanoseconds, a sensor configured to: detect, during a first portion ofthe emission time period, a first emission from the emissive species,and detect, during a second portion of the emission time period, asecond emission from the emissive species, and processing circuitrycapable of identifying a characteristic of the emissive species based ona difference between a property of the first emission detected duringthe first portion of the emission time period and a property of thesecond emission detected during the second portion of the emission timeperiod.

In an exemplary set of embodiments, a method comprises determining anidentity or characteristic of a chemical/biological species by: exposingan emissive species to an electromagnetic radiation spectrum generatedby a source of electromagnetic radiation and having a range that spansgreater than or equal to 50 nm, the emissive species associated with thechemical/biological species, and detecting a detectable emissionproduced by the emissive species, wherein the detectable emission, ifpresent, corresponds to the identity or characteristic of thechemical/biological species.

In an exemplary set of embodiments, a method comprises determining anidentity or characteristic of a chemical/biological species bycombining: a first electromagnetic radiation signal and a secondelectromagnetic radiation signal, wherein the first electromagneticsignal comprises at least a first photon emission event occurring within10 nanoseconds of an excitation event that caused the first photonemission event, and a second electromagnetic signal comprising at leasta second photon emission event occurring after 10 nanoseconds of theexcitation event that caused the second photon emission event, whereinthe excitation event comprises an electromagnetic radiation spectrum,wherein a first portion of the electromagnetic radiation spectrumcomprises a wavelength of between 425 nm and 475 nm, and wherein asecond portion of the electromagnetic radiation spectrum comprises awavelength of between 525 nm and 725 nm.

In some embodiments, at least one emission is selected from the groupconsisting of subtractive color, reflected color, chemiluminescence,prompt-fluorescence, delayed-fluorescence, prompt-phosphorescence, ordelayed-phosphorescence. In some embodiments, the source ofelectromagnetic radiation comprises an LED component.

In some embodiments, luminescent materials are excited and a smartphonedetects a steady-state photon emission event and a non-steady-stateemission event or optionally a non-steady-state photon emission event.In some embodiments, the emissive material absorbs light emitted from asmartphone. In some embodiments, the emissive material absorbs light ata wavelength of 440 nm or higher. In some embodiments, the detectablesignal comprises subtractive color, reflected color, chemiluminescence,prompt-fluorescence, delayed-fluorescence, prompt-phosphorescence, ordelayed-phosphorescence emission. In some embodiments, the emissivematerial comprises a TADF emission, an organometallic compound, ametallorganic material, a Europium complex, and/or an organic moleculecontaining iodine or bromine atoms.

In some embodiments, the emissive material is electronically coupled toor connected to a heavy atom. In some embodiments, the emissive materialcomprises metalloporphyrin. In some embodiments, the emissive materialis excited by a white light source. In some embodiments, the emissivematerial is excited by an LED emitting between 440 and 700 nm. In someembodiments, the emissive material is used in a lateral flow assay orvertical flow assay. In some embodiments, the emissive material is usedin product authentication.

In some embodiments, the emissive material is used to detect a gas, achemical, an antibody, an antigen, a virus, a bacteria, an allergen,mold, spore, and/or a pathogen. In some embodiments, the emissivematerial is used to detect ionizing radiation. In some embodiments, theemissive material is used to detect a thermal exposure. In someembodiments, the emissive material is used to detect an ultravioletlight exposure. In some embodiments, the emissive material is used todetect moisture and/or oxygen exposure.

In an exemplary set of embodiments, a system comprises a source ofelectromagnetic radiation associated with a consumer electronic device,a sensor associated with the consumer electronic device, and an emissivespecies capable of producing a detectable signal by the sensor, thedetectable signal having one or more delayed emissions of greater thanor equal to 10 nanoseconds.

In an exemplary set of embodiments, a method comprises using a consumerelectronic device to determine an identity or characteristic of achemical/biological species, wherein the consumer electronic devicecomprises a source of a spectrum of electromagnetic radiation, andexposing an emissive species to the spectrum of electromagneticradiation such that the emissive species produces a detectable emissionwhich corresponds to the identity or characteristic of thechemical/biological species and which is detectable by the consumerelectronic device.

In some embodiments, a first portion of the electromagnetic radiationspectrum comprises a wavelength of between 425 nm and 475 nm and whereina second portion of the electromagnetic radiation spectrum comprises awavelength of between 525 nm and 725 nm. In some embodiments, thedetectable signal comprises one or more delayed emissions of greaterthan or equal to 10 nanoseconds. In some embodiments, at least oneemission is selected from the group consisting of subtractive color,reflected color, chemiluminescence, prompt-fluorescence,delayed-fluorescence, prompt-phosphorescence, ordelayed-phosphorescence. In some embodiments, the source ofelectromagnetic radiation comprises an LED component. In someembodiments, a rolling shutter mechanism associated with the system ormethod.

In some embodiments, luminescent materials are excited and a smartphonedetects a steady-state photon emission event and a non-steady-stateemission event or optionally a non-steady-state photon emission event.In some embodiments, the emissive material absorbs light emitted from asmartphone. In some embodiments, the emissive material absorbs light ata wavelength of 440 nm or higher. In some embodiments, the detectablesignal comprises subtractive color, reflected color, chemiluminescence,prompt-fluorescence, delayed-fluorescence, prompt-phosphorescence, ordelayed-phosphorescence emission. In some embodiments, the emissivematerial comprises a TADF emission. In some embodiments, the emissivematerial comprises an organometallic compound. In some embodiments, theemissive material comprises a metallorganic material. In someembodiments, the emissive material comprises Europium complex. In someembodiments, the emissive material comprises an organic moleculecontaining iodine or bromine atoms. In some embodiments, the emissivematerial is electronically coupled to or connected to a heavy atom. Insome embodiments, the emissive material comprises metalloporphyrin. Insome embodiments, the emissive material is excited by a white lightsource. In some embodiments, the emissive material is excited by an LEDemitting between 440 and 700 nm. In some embodiments, the emissivematerial is used in a lateral flow assay. In some embodiments, theemissive material is used in product authentication. In someembodiments, the emissive material is used to detect a gas, a chemical,an antibody, an antigen, a virus, a bacteria, an allergen, mold, spore,and/or a pathogen. In some embodiments, the emissive material is used todetect ionizing radiation. In some embodiments, the emissive material isused to detect a thermal exposure.

In some embodiments, a global shutter associated with the method orsystem.

In some embodiments, an enclosure is provided and configured to receivethe consumer electronic device. In some embodiments, the enclosure isconfigured to position the consumer electronic device relative to anemissive species. In some embodiments, the enclosure is configured toprevent external light from interacting with the sensor. In someembodiments, the enclosure contains a source of electromagneticradiation capable of exciting the emissive species.

In an exemplary set of embodiments, a kit comprises an enclosureconfigured to receive a consumer electronic device, the consumerelectronic device comprising a sensor and a source of electromagneticradiation associated with the enclosure and/or consumer electronicdevice, wherein: the enclosure is configured to position the consumerelectronic device relative to an emissive species, if present, such thatthe sensor can detect a detectable emission from the emissive species,and the enclosure is configured to prevent external light frominteracting with the sensor.

Additional Exemplary Embodiments

The following embodiments are provided for exemplary purposes and arenot intended to be limiting. Other embodiments as described herein arealso possible.

1. A device capable of exciting an object and reading a patterngenerated by luminescence and/or reflected/scattered electromagneticradiation wherein at least one emissive species generates a signal thatchanges over the course of the reading of the pattern.

-   a. A device as in embodiment 1 wherein the excitation is produced by    one of more bursts of electromagnetic radiation that excite all of    the emissive species.-   b. A device as in embodiment 1, wherein the reading of the pattern    is accomplished by acquiring a single image.-   c. A device as in embodiment 1, wherein the reading of the pattern    is accomplished by acquiring multiple images.-   d. A device as in embodiment 1 wherein the excitation is    accomplished by pulsed and/or modulated electromagnetic radiation.-   e. A device as in embodiment 1 wherein the excitation is    accomplished by a flash lamp, LED, laser, and/or a fluorescent    light.-   f. A device as in embodiment 1 wherein the excitation method is    controlled by an optical shutter, light valve, optical modulator,    refractory material, or mirror.-   g. A device as in embodiment 1 wherein excitation is performed at    different wavelengths capable of independently exciting different    emissive species.-   h. A device as in embodiment 1 wherein one of more images are    collected with different delays from a burst of electromagnetic    radiation or modulated electromagnetic radiation at one or more    wavelengths.-   i. A device as in embodiment 1 wherein the excitation varies    throughout the reading of the pattern,-   j. A device as in embodiment 1 having an integrated excitation and    image capture component-   k. A device as in embodiment 1 wherein the excitation and image    capture components are separate.-   l. A device as in embodiment 1 wherein the device incorporates a    CMOS imaging unit.-   m. A device as in embodiment 1 wherein the device is a smartphone.-   n. A device as in embodiment 1 wherein the device can dynamically    change the method of excitation and reading of an object during the    course of taking measurements.-   o. A device as in embodiment 1 wherein the instructions for    excitation and reading of an image are provided from another optical    image, software, form an external source via wireless communication.-   p. A device as in embodiment 1 wherein the device is capable of    triggering a non-optical excitation of at least one emissive    component by electrical, mechanical, particle, or chemical    stimulation.    2. An article comprising one or more emissive species (e.g., dyes,    materials) that have excited state lifetimes more than 10    nanoseconds.    a. An article as in embodiment 2 wherein a coating of the article    has information that reveals the identity and/or status of a product    that is associated with the article.    b. An article as in embodiment 2 that is a coating on a pill, a    capsule, or the physical packaging of a product.    c. An article as in embodiment 2 wherein part of the article    comprises a bar code or matrix code.    d. An article as in embodiment 2 wherein information on how the    article is to be read is encoded.    e. An article as in embodiment 2 wherein the emissive dyes with    lifetimes more than 10 nanoseconds respond to their environment to    reveal information about the status of the product.    f. An article as in embodiment 2 wherein the emissive signal is    created, changed, or enhanced with a lifetime greater than 10    nanoseconds in response to its environment or exposure history.    g. An article as in embodiment 2 wherein the emissive signal is    created by an inorganic phosphor.    h. An article as in embodiment 2 wherein the emissive signal is    created by an inorganic/organic composition.    i. An article as in embodiment 2 with an emissive material that    contains bismuth.    j. An article as in embodiment 2 with an emissive material that    contains iridium, platinum, rhenium, gold, or copper.    k. An article as in embodiment 2 with an emissive material that    contains a lanthanide or actinide metal.    m. An article as in embodiment 2 with an emissive material contains    bromide, iodide, sulfur, selenium, telluride, phosphorous, antimony,    tin, lead, mercury, or cadmium.    n. An article as in embodiment 2 with an emissive material that    displays a thermally activated delayed emission.    o. An article as in embodiment 2 with an emissive material that can    diffuse to change its location in the article.    p. An article as in embodiment 2 which is a liquid.    q. An article as in embodiment 2 which is a gel.    r. An article as in embodiment 2 which is composite of solids,    liquids, and/or gels.    s. An article as in embodiment 2 which has optical structures that    focus or waveguide light.    u. An article as in embodiment 2 which contains a hologram    v. An article as in embodiment 2 which contains a bar or matrix code    w. An article as in embodiment 2 that is produced by the combination    of an initial test strip that gives an emissive response after    application of a material of interest to it.    x. An article as in embodiment 2 which has optical structures that    result in directional emission or polarization of emitted light.    3. A method of reading a biological diagnostic assay wherein an    imaging device provides a readout from the assay by detecting two or    more signals emanating optionally from subtractive color, reflected    color, scattering, chemiluminescence, prompt-fluorescence,    delayed-fluorescence, prompt-phosphorescence, or    delayed-phosphorescence.    4. A method as in embodiment 3, wherein the signal is an image    captured by a smartphone, digital camera or equivalent.    5. A method as in embodiment 3, wherein the signal is used to create    a digital intensity profile.    6. A method as in embodiment 3, wherein the signal can be used to    give information about the quantity and/or presence of a biological    species.    7. A method as in embodiment 3, wherein the two or more signals come    from more than one of the following processes: subtractive color,    reflected color, scattering, chemiluminescence, prompt-fluorescence,    delayed-fluorescence, prompt-phosphorescence, or    delayed-phosphorescence.    8. A method as in embodiment 3, wherein a colorimetric signal is    used with a prompt-fluorescence signal.    9. A method as in embodiment 3, wherein a colorimetric signal is    used with a delayed-fluorescence signal.    10. A method as in embodiment 3, wherein a colorimetric signal is    used with a prompt-phosphorescence signal.    11. A method as in embodiment 3, wherein a colorimetric signal is    used with a delayed-phosphorescence signal.    12. A method as in embodiment 3, wherein a colorimetric signal is    used with a chemiluminescence signal.    13. A method as in embodiment 3, wherein a prompt-fluorescence    signal is used with a delayed-phosphorescence signal.    14. A method as in embodiment 3, wherein at least one signal is    collected in a steady-state mode and at least one other signal is    collected using a time synchronized light source.    15. A method as in embodiment 3, wherein at least one signal is    collected when the time synchronized light source is off and at    least another signal is collected when the time synchronized light    source is on.    16. A method as in any previous embodiment, wherein at least one    signal is collected while the assay is illuminated by one or more    LED light sources.    17. A method as in any previous embodiment, wherein at least one    signal is characteristic of the cycle time of a modulated light    excitation.    18. A method as in any previous embodiment, wherein at least one of    the light sources is the flash from a smartphone or digital camera.    19. A method as in any previous embodiment, wherein the biological    diagnostic is a lateral flow or vertical flow assay.    20. A method as in any previous embodiment, wherein the biological    diagnostic is a loop-mediated isothermal amplification (LAMP) for    nucleic acid detection    21. A method as in any previous embodiment, wherein the    delayed-phosphorescence is associated with a europium or terbium    complex.    22. A method as in any previous embodiment, wherein nanoparticles    are used to provide a colorimetric signal.    23. A method as in any previous embodiment, wherein nanoparticles    are used to provide an emissive signal.    24. A method as in any previous embodiment, wherein excited state    lifetime information is part of the signal.    25. A method as in any previous embodiment, wherein polarized light    is used.    26. A method as in any previous embodiment, wherein changes in the    local environment affect the signal.    27. A method as in any previous embodiment, wherein a biomolecular    recognition event affects the signal.    28. A method as in any previous embodiment, wherein more than one    biological diagnostic assay can be simultaneously analyzed.    29. A method as in any previous embodiment, wherein the hardware can    be used for both steady-state and time-gated measurements by    changing the firmware or software.    30. A method of reading a biological diagnostic assay using    non-steady state illumination and a smartphone or digital camera.    31. A method as in any previous embodiment, wherein a rolling    shutter mechanism is used for the detection of signals.    32. A method as in any previous embodiment, wherein the non-steady    state illumination is used to read a prompt-fluorescence,    delayed-fluorescence, prompt-phosphorescence, or    delayed-phosphorescence signal.    33. A method as in any previous embodiment, wherein the biological    diagnostic assay is a lateral flow assay.    34. A method as in any previous embodiment, wherein changes in the    lifetime, wavelength, intensity or polarization of emissive signals    detected as a result of a binding event allows for discrimination    between specific and non-specific binding events.    35. A method as in any previous embodiment, wherein image or images    are optionally collected, one or more times, in different sequences    to provide image orientation, ambient light correction, the signal    or signals associated with the biological event of interest, a    signal for calibration or quantification of the biological event,    the temperature under which the assay is performed, authentication    or tracking of the assay, the thermal history of the assay, and    fiducial signals for image alignment.    36. A method as in any previous embodiment, wherein the signals    collected can be performed a part of a personal health monitoring    system, wherein an individual can perform tests that are transmitted    to medical experts.

EXAMPLES Example 1—Direct Capture System

Human IgG was conjugated to 200 nm Europium (Eu) beads and Goatanti-human IgG/IgM was immobilized onto nitrocellulose. Lateral flowdevices containing pre-treated glass fiber sample pads and cover tapewere then assembled. Dilutions of the Eu-labeled Human IgG in bufferwere deposited onto the sample/conjugate pad of the lateral flow deviceand the resultant developed by dipping into buffer. After a set time hadelapsed, the chromatographic result was imaged/analyzed using acustomized smartphone device, holder, and algorithm/app (FIG. 8 ).

Example 2—Serological Assay System—Antibody Detection

Chicken IgY (control line), Goat anti-Human IgA (test line 1), Donkeyanti-Human IgM (test line 2), and Donkey anti-Human IgG (test line 3)were immobilized onto nitrocellulose and lateral flow devices assembled.Eu-labeled Donkey anti-Chicken and Eu-labeled Mouse anti-HIS were thendeposited onto the sample/conjugate pad followed by specific COVID-19antigen(s) such as HIS-tagged Nucleoprotein (NP) antigen. The resultantdevices were then tested using clinical-derived Human COVID-19 antibodypositive and negative saliva or blood/serum samples, imaged/analyzedusing a customized smartphone device, holder, and algorithm/app. FIG. 9shows an example of a negative assay with only the control linedetected. FIG. 10 shows an example of a positive assay with the IgG linedetected in addition to the control line.

Example 3—Sandwich Assay System—Antigen Detection

Coronavirus NP capture antibodies were immobilized onto nitrocelluloseand lateral flow devices assembled. Coronavirus COVID-19 SARS NPdetection antibodies, conjugated to 200 nm Eu beads were mixed withCoronavirus COVID-19 NP antigen in buffer or Human saliva, and the assaydeveloped. The results were then imaged/analyzed using a customizedsmartphone device, holder, and algorithm/app. FIG. 11 shows an exampleof a negative assay with no line detected. FIG. 12 shows an example of apositive assay with a line detected.

Example 4—Europium Based Lateral Flow Assay

FIG. 13 shows representative photographs of a Europium-based lateralflow assay imaged using a customized smartphone device, holder, andalgorithm/app under different camera settings. At faster shutter speeds(shorter exposures) the rolling shutter effect may be clearly observedeliminating background signals (prompt fluorescence) originating fromthe nitrocellulose, cover tape, etc. In this case the UV-LED off signal(image portion) represents a steady-state signal and the light offrepresents a time synchronized signal (image portion).

Example 5—Exemplary System

FIGS. 14A-14C show an exemplary system for capturing data from an assay,according to some embodiments described herein. For example, FIG. 14Ashows a case configured to integrate with a smartphone, comprising a UVLED source and permits the camera of the smartphone to be exposed. FIG.14B shows an exemplary holder comprising a portion configured to receivethe smartphone, and a sample port configure to receive a sample (e.g.,an immunoassay cassette). FIG. 14C shows an exemplary output from acustom smartphone software that provides, for example, an image of thesample and a corresponding plot of intensity.

An illustrative device (FIG. 14D) that prevents stray light frominterfering with the measurement of an immunoassay, accepts animmunoassay cassette, positions the camera of a smart phone relative tothe assay for interrogation, and contains a combination of componentssuch as a light emitting diode (LED), an optical filter, a polarizer, alens, a battery, a diode (indicator light) and a PCB. The device designis modular to allow for: 1) the interchange of components to addressdifferent smartphone types and different assay cartridges; 2)efficiencies in manufacturing; and 3) reduction of waste andenvironmental impact. The device design may also be configured to readassays in either reflectance or transmission modes.

Another illustrative device (FIGS. 14E-14F) provides rapid, point ofneed diagnostics. For example, FIG. 14F shows a schematics of a designrendering of the components of the diagnostic: set up tray withinstructions for use (top left), integrated cassette and samplecollection swab (top middle), smartphone adapter (top right), andoverall workflow (bottom). Other components are also possible.

Example 6—Exemplary Computational Analysis

An exemplary computational procedure for detecting test strip binding ona given assay is as follows: (1) Machine vision methods such as objectdetection, edge detection and shape estimation are employed to locateworkpiece datums and establish a reference coordinate frame. (2)Emission intensity is measured within the localized binding region ofthe assay. (3) Methods of curve/surface fitting and smoothing areapplied to disambiguate the measured signal. (4) Peaks are detected inthe enhanced signal and correlated with nominal test strip locations toreport presence/absence of significant test strip binding events. FIG.15A shows an image wherein machine vision has identified the area of thekey boundaries of an assay and the locations of the control and testsignal. FIG. 15B shows integrated line data obtained from the image inFIG. 15A showing the in circles at the top of the peaks, whichcorresponds to the locations of the vertical lines projected on theimage.

Example 7—Simultaneously Imaging Multiple LFAs

FIG. 16 shows representative photographs of 5 Europium-based ladderassays simultaneously imaged using a customized smartphone device,holder, and algorithm/app under different camera settings. The rollingshutter effect may be clearly observed at faster shutter speeds (shorterexposures). Higher throughputs are also feasible.

Example 8—Synthesis ofEuropium-tris(6,6,7,7,8,8,8-heptafluoro-2,2-dimethylortane-3,5-dione)[Eu(fod)₃] and Michler's Ketone (MK) Complex, Eu(fod)₃-MK

Europium-tris(6,6,7,7,8,8,8-heptafluoro-2,2-dimethyloctane-3,5-dione)[Eu(fod)₃] (0.050 g) and Michler's ketone (0.013 g) was placed in anoven-dried. Shlenck flask. The reaction vessel was placed under vacuumfor 30 min, and then back filled with argon. Toluene (10 mL) was addedvia a syringe. The reaction was stirred for 5 min at room temperatureuntil all of the starting materials dissolved. A light-yellow solutionof Eu(fod)₃-MK was obtained. Intense red emission was observed when thesample was irradiated with a blue LED.

Example 9—Preparation of 2-acetyl-9-ethylcarbazole

9-Ethylcarbazole (2.0 g, 0.010 mol) and acetyl chloride (0.884 g) wasdissolved in dry dichloromethane (100 mL), and the solution cooled to 0°C. under argon. To this solution, aluminum chloride (1.5 g) was added insmall aliquots over 30 min. The reaction was then allowed to warm toroom temperature and stirred for 5 hours. Concentrated hydrochloric acid(5 mL) was slowly added to the reaction mixture, followed by 1 Mhydrochloric acid (30 mL). The organic layer was separated and driedover MgSO₄. The solvent was removed and the residue purified by flashchromatography (2:1 dichloromethane/hexanes) to afford the2-acetyl-9-ethylcarbazole (1.43 g).

Example 10—Preparation of1-(9-ethyl-9H-carbazol-3-yl)-4,4,4-trifluorobutane-1,3-dione

To a 100 mL flask purged with argon was added a solution of potassiumtort-butoxide in THE (1M, 10.1 mL) and the reaction vessel cooled to 0°C. A solution of 2-acetyl-9-ethylcarbazole (1.2 g) and ethyltrifluoroacetate (0.72 g) in dry THF (10 mL) was slowly added. Thereaction was then allowed to warm to RT and stirred for 8 hours. Thesolvent was removed under vacuum and 1M hydrochloric acid (12 mL) wasslowly added, followed by water (30 mL) and dichloromethane (50 mL). Theorganic layer was separated, washed with water, and dried over sodiumsulfate. The solvent was removed to afford the β-diketo ligand (1.25 g).

Example 11—Preparation of an Europium(III) Complex with4,4,4-Trifluoro-1-(ethylcarbazole)-1,3-butanedione as Ionic Ligands

4,4,4-Trifluoro-1-(ethylcarbazole)-1,3-butanedione (200 mg) and1,10-Phenanthroline monohydrate (39.6 mg) was dissolved in ethanol (30mL) under argon. Sodium hydroxide (24 mg) was then added. The reactionwas stirred for 30 min at 60° C. and then a solution of Europium(iii)chloride hexahydrate (73.3 mg) in ethanol (10 mL) was slowly added. Thereaction was stirred at 60° C. for 8 hours under argon. The reaction wascooled to T and the solids collected by filtration and washed withethanol. The crude complex was then dissolved in a small amount ofdichloromethane mL) and any insolubles removed. Ethanol was then addedto the dichloromethane solution to cause the europium complex toprecipitate. The solids were again collected by filtration and driedunder vacuum to afford the complex in pure form. Yield: 188 mg.

Example 12—Preparation of 2-acetyl-9-phenylcarbazole

9-Phenylcarbazole (1.0 g, 0.00373 mol) and acetyl chloride (0.322 g.0.00410 mol) was dissolved in dry dichloromethane (100 mL) and thesolution cooled to 0° C. under argon. To this solution, aluminumchloride (0.547 g) was added in small portions. The reaction was thenallowed to warm to room temperature and stirred for 5 hours.Concentrated hydrochloric acid (5 mL) was then slowly added to thereaction mixture, followed by 1 M hydrochloric acid (30 mL). The organiclayer was separated and dried over MgSO₄, the solvent removed, and theresidue purified by flash chromatography (2:1 dichloromethane/hexanes)to afford the ketone (0.562 g, 62% yield).

Example 13—Preparation of4,4,4-Trifluoro-1-(phenylcarbazole)-1,3-butanedione

To a 100 mL flask purged with argon was added a solution of potassiumtert-butoxide in THF (1M, 7.0 mL). The solution was then cooled to 0° C.A solution of 2-acetyl-9-ethylcarbazole (1.0 g) and ethyltrifluoroacetate (0.50 g) in dry THF (10 mL) was slowly added. Thereaction was allowed to warm to RT and stirred for 8 hours. The solventwas removed under vacuum and 1M hydrochloric acid (7 mL) was slowlyadded followed by water (30 mL) and dichloromethane (50 mL). The organiclayer was separated, washed with water, and dried over sodium sulfate.The solvent was removed and the residue purified by silica gel flashchromatography eluted with dichloromethane/hexanes (1:1) to afford theß-diketo ligand (0.92 g, 69% yield).

Example 14—Preparation of an Europium(III) Complex with4,4,4-Trifluoro-1-(phenylcarbazole)-1,3-butanedione as Ionic Ligands

4,4,4-Trifluoro-1-(9-phenyl-9H-carbazol-3-yl)butane-1,3-dione (200 mg,0.524 mmol) and 1,10-Phenanthroline monohydrate (34.7 mg, 0.175 mmol)was dissolved in ethanol (30 mL) under argon. Sodium hydroxide (21 mg)was then added. The reaction was stirred for 30 min at 60° C. and then asolution of Europium(III) chloride hexahydrate (64.1 mg, 0.175 mmol) inethanol (10 mL) was slowly added. The reaction was stirred at 60° C. for8 hours under argon. The reaction was cooled to RT and the solidscollected by filtration and washed with ethanol. The crude complex wasthen dissolved in a small amount of dichloromethane (˜5 mL) and theinsolubles removed. Hexanes was then added to the dichloromethanesolution to cause the europium complex to precipitate. The solids wereagain collected by filtration and dried under vacuum to afford thecomplex in pure form (188 mg, 73% yield).

Example 15—Preparation4-(4,6-dichloro-1,3,5-triazin-2-yl)-N,N-diethylaniline

N,N-Diethylaniline (10.0 g, 0.067 mol) and cyanuric chloride (12.4 g,0.067 mol) was dissolved in dry dichloromethane (200 mL) under argon.Aluminum chloride (8.93 g, 0.067 mol) was added in small portions over30 min. The reaction was stirred for 4 hours at 0° C. and then allowedto warm to morn temperature and stirred for 16 hours. Concentratehydrochloric acid (50 mL) was slowly added, followed by water (150 mL).The organic layer was separated, washed with water, and dried overanhydrous MgSO₄. The solvent was removed and the residue purified bysilica gel flash chromatography with dichloromethane/hexanes (1:1) aseluent. The pure product was crystalized from dichloromethane andhexanes (8.16 g, 41% yield).

Example 16—Preparation of2-(N,N-Diethylanilin-4-yl)-4,6-bis(3,5-dimethyl-pyrazol-1-yl)-1,3,5-triazine(dpbt)

3,5-Dimethylpyrazole (1.0 g, 0.0104 mol) was dissolved in dry THE (20mL) under argon. A solution of Potassium tert-Butoxide (12% inTetrahydrofuran, ca. 1 M, 10.4 ML) was added. The reaction was stirredfor 30 min at room temperature and cooled to 0° C. A solution of4-(4,6-dichloro-1,3,5-triazin-2-yl)-N,N-diethylaniline (1.47 g, 0.00495mol) in dry THF (15 mL) was slowly added and the reaction allowed towarm to room temperature and stirred for 8 hours, and then heated to 80°C. under argon for 16 hours. The reaction was then cooled to roomtemperature and the solvent removed under vacuum. The residue waspurified by silica gel flash chromatography with dichloromethane/ethylacetate (3:2) as eluent. The pure product was crystalized fromdichloromethane and hexanes (1.17 g, % yield).

Example 17—Preparation2-(N,N-di-ethylanilin-4-yl)-4,6-bis(pyrazol-1-yl)-1,3,5-triazine (bpt)

Pyrazol (0.434 g, 0.00639 mol) was dissolved in dry THF (30 mL) underargon. A solution of potassium cert-butoxide (12% in tetrahydrofuran,ca. 1 M, 6.10 mL) was added. The reaction was stirred for 30 min at roomtemperature and cooled to 0° C. A solution of4-(4,6-dichloro-1,3,5-triazin-2-yl)-N,N-diethylaniline (1.00 g, 0.00304mol) in dry THF (15 mL) was slowly added and the reaction allowed towarm to room temperature and stirred for 8 hours, and then heated to 80°C. under argon for 16 hours. The reaction was then cooled to roomtemperature and the solvent removed under vacuum. The residue waspurified by silica gel flash chromatography with dichloromethane/ethylacetate (1:1) as eluent. The pure product was crystalized fromdichloromethane and hexanes (0.23 g, 21% yield).

Example 18—Preparation of Europiumtris-thenoyltrifluoroacetonato-2-(N,N-diethylanilin-4-yl)-4,6-bis(3,5-dimethyl-pyrazol-1-yl)-1,3,5-triazinecomplex [Eu(tta)₃(dpbt)]

A solution of Eu(tta)₃·3H₂O (100 mg, 0.115 mmol) in THF (10 mL) wasadded to a solution of bpt (49.3 mg, 0.115 mmol) in THF (10 mL) and themixture stirred for 30 min at room temperature. The solvent was removedunder vacuum and the residue dissolved in a small amount ofdichloromethane. Hexanes was added and the yellow precipitate collectedby filtration to afford the Eu(tta)₃(dpbt) (126 mg, 88%).

Example 19—Preparation of Europiumtris-thenoyltrifluoroacetonato-2-(N,N-di-ethylanilin-4-yl)-4,6-bis(pyrazol-1-yl)-1,3,5-triazinecomplex [Eu(tta)₃(bpt)]

A solution of Eu(tta)₃·3H₂O (100 mg, 0.115 mmol) in THF (10 mL) wasadded to a solution of bpt (41.5 mg, 0.115 mmol) in THF (10 mL) and themixture was stirred for 30 min at room temperature. The solvent wasremoved under vacuum and the residue was dissolved in small amount ofdichloromethane. Hexanes was added and the yellow precipitates werecollected by filtration to afford the Eu(tta)₃(bpt) (108 mg, 80%).

Example 20

The following example demonstrates the use of exemplary emissivespecies.

FIGS. 18A-18D show images collected using an iPhone 11 and external(pulsed) white light LED of drop-cast samples of: a) Eu(fod)₃-MK; b)Eu(tta)₃(dpbt); c) Eu(tta)₃(bpt); and d) Eu(pfppd)₃(tpy), as prepared asdescribed above.

FIG. 19 shows samples of Eu(fod)₃-MK, with or without PMMA, drop-cast orspin-coated onto plain labels or labels pre-printed with a matrix (2D)barcode. Images collected using an iPhone 11 and external (pulsed) whitelight LED, with or without the presence of room lighting.

FIG. 20 shows samples of Eu(tta)₃(dpbt) in PMMA analyzed using a: a)fluorimeter; or b) an iPhone 11 with external (pulsed) white light LED,with or without the presence of room lighting.

FIG. 21 is a plot of fluorescence intensity versus excitation wavelengthfor a drop-cast sample of Eu(pfppd)₃(tpy) excited at various excitationwavelengths in a fluorimeter.

FIGS. 22A-22B show images of drop-cast samples of Eu(tta)₃(bpt) in aF8BT/PMMA mixture at: FIG. 22A) 0.6 mg/mL; and FIG. 22B) 1 mg/mL. Imageswere obtained using a commercially available flashlight app to strobethe white light LED of an iPhone 11.

FIGS. 23A-23B show images of airbrushed samples of Eu(tta)₃(bpt) in aF8BT/PMMA analyzed with (FIG. 23A) or without (FIG. 23B) the presence ofroom lighting, with images obtained using a commercially availableflashlight app to strobe the white light LED of an iPhone 11.

FIGS. 24A-24B show images of a sample of Erythrosin B, a commerciallyavailable food coloring, incorporated into a Poly Vinyl Alcohol (PVA)matrix. The sample was imaged using an iPhone 11 under ambient (room)lighting (FIG. 24A) and in the dark using an external (pulsed) whitelight LED (FIG. 24B).

Example 21

The following example demonstrates the use of a smartphone (or otherconsumer electronic device) in accordance with the embodiments describedherein e.g., for authentication of a sample.

FIGS. 25A-25B show images of a sample of tan colored leather, withauthentication tag airbrushed on top. The sample was imaged with aniPhone 11 using a custom application (app) and pulsed UV LED excitationsource, with pulsed UV light source off (FIG. 25A) and on (FIG. 25B) ina lit room.

FIGS. 26A-26B show images of a sample of blue colored leather, withauthentication tag airbrushed on top. The sample was imaged with aniPhone 11 using a custom application (app) and pulsed UV LED excitationsource with the pulsed UV light source off (FIG. 26A) and on (FIG. 26B)in a lit room.

FIGS. 27A-27B show images of a clear glass, alcohol filled perfumebottle, with authentication tag airbrushed on one side. The sample wasimaged with an iPhone 11 using a custom application (app) and pulsed UVLED excitation source with the pulsed UV light source off (FIG. 27A) andon (FIG. 27B) in a lit room.

FIGS. 28A-28B show images of a white cardboard box, with authenticationtag (smart logo) airbrushed on one side. The sample was imaged with aniPhone 11 using a custom application (app) and pulsed UV LED excitationsource, with the pulsed UV light source off (FIG. 28A) and on (FIG. 28B)in a lit room.

FIGS. 29A-29B show images of a printed 2D (matrix) barcode on a whitelabel, with authentication tag airbrushed on top. The sample was imagedwith an iPhone 11 using a custom application (app) and pulsed UV LEDexcitation source, with the pulsed UV light source off (FIG. 29A) and on(FIG. 29B) in a lit room.

FIGS. 30A-30B show images of a printed 2D (matrix) barcode on a whitebox, with authentication tag airbrushed on top. The sample was imagedwith an iPhone 11 using a custom application (app) and pulsed UV LEDexcitation source, with the pulsed UV light source off (FIG. 30A) and on(FIG. 30B) in a lit room.

FIGS. 31A-31B shows images of a printed 2D (matrix) barcode on a blacknotebook, with authentication tag airbrushed on top. The sample wasimaged with an iPhone 11 using a custom application (app) and pulsed UVLED excitation source, with the pulsed UV light source off (FIG. 31A)and on (FIG. 31B) in a lit room.

FIG. 32A shows an image of a drop-cast sample of Eu(fod)3-MK on a glasscoverslip, imaged with an iPhone 11 using a custom application (app) andpulsed excitation source. The images were collected using the same ISOsetting but different shutter speeds. The top half of the coverslip hadbeen exposed to diethylamine for 2 minutes, the bottom half had not beenexposed.

FIG. 32B shows an image of a drop-cast sample of Eu(fod)3-MK on a glasscoverslip, imaged with an iPhone 11 using a custom application (app) andpulsed excitation source. The images collected using the same ISOsetting but different shutter speeds. The top half of the coverslip hadbeen exposed to water for 15 minutes, the bottom half had not beenexposed.

FIGS. 33A-33B show images of a drop-cast sample of PdOEP on a glasscoverslip in an air-free environment inside a vacuum chamber, imagedwith an iPhone 11 and pulsed white light LED excitation source, before(FIG. 33A) and after (FIG. 33B) exposure to air/oxygen.

FIGS. 34A-34B show images of a cast film of PdOEP inside a glass vial,imaged with an iPhone 11 using a custom application (app) and pulsedwhite light LED excitation source, before (FIG. 34A) and after (FIG.34B) exposure to air/oxygen. FIG. 35A shows chemical structures ofexemplary oligomeric/polymeric white light excitable Eu-based delayedemitters (PCBH)₆Eu₂(Phen)₂, (PCBH)(PCH)Eu(bpt), and (PCBH)(PCH)Eu(Phen).

FIG. 35B-35C show images of a solid sample of (PCBH)(PCH)Eu(bpt) in aglass vial (FIG. 35B) and drop-cast on white paper (FIG. 35C), imagedwith an iPhone 11 using a custom application (app) and the iPhone'sflash LED.

While several embodiments of the present invention have been describedand illustrated herein, those of ordinary skill in the art will readilyenvision a variety of other means and/or structures for performing thefunctions and/or obtaining the results and/or one or more of theadvantages described herein, and each of such variations and/ormodifications is deemed to be within the scope of the present invention.More generally, those skilled in the art will readily appreciate thatall parameters, dimensions, materials, and configurations describedherein are meant to be exemplary and that the actual parameters,dimensions, materials, and/or configurations will depend upon thespecific application or applications for which the teachings of thepresent invention is/are used. Those skilled in the art will recognize,or be able to ascertain using no more than routine experimentation, manyequivalents to the specific embodiments of the invention describedherein. It is, therefore, to be understood that the foregoingembodiments are presented by way of example only and that, within thescope of the appended claims and equivalents thereto, the invention maybe practiced otherwise than as specifically described and claimed. Thepresent invention is directed to each individual feature, system,article, material, kit, and/or method described herein. In addition, anycombination of two or more such features, systems, articles, materials,kits, and/or methods, if such features, systems, articles, materials,kits, and/or methods are not mutually inconsistent, is included withinthe scope of the present invention.

The indefinite articles “a” and “an,” as used herein in thespecification and in the claims, unless clearly indicated to thecontrary, should be understood to mean “at least one.”

The phrase “and/or,” as used herein in the specification and in theclaims, should be understood to mean “either or both” of the elements soconjoined, i.e., elements that are conjunctively present in some casesand disjunctively present in other cases. Other elements may optionallybe present other than the elements specifically identified by the“and/or” clause, whether related or unrelated to those elementsspecifically identified unless clearly indicated to the contrary. Thus,as a non-limiting example, a reference to “A and/or B,” when used inconjunction with open-ended language such as “comprising” can refer, inone embodiment, to A without B (optionally including elements other thanB); in another embodiment, to B without A (optionally including elementsother than A); in yet another embodiment, to both A and B (optionallyincluding other elements); etc.

As used herein in the specification and in the claims, “or” should beunderstood to have the same meaning as “and/or” as defined above. Forexample, when separating items in a list, “or” or “and/or” shall beinterpreted as being inclusive, i.e., the inclusion of at least one, butalso including more than one, of a number or list of elements, and,optionally, additional unlisted items. Only terms clearly indicated tothe contrary, such as “only one of” or “exactly one of,” or, when usedin the claims, “consisting of,” will refer to the inclusion of exactlyone element of a number or list of elements. In general, the term “or”as used herein shall only be interpreted as indicating exclusivealternatives (i.e. “one or the other but not both”) when preceded byterms of exclusivity, such as “either,” “one of,” “only one of,” or“exactly one of.” “Consisting essentially of,” when used in the claims,shall have its ordinary meaning as used in the field of patent law.

As used herein in the specification and in the claims, the phrase “atleast one,” in reference to a list of one or more elements, should beunderstood to mean at least one element selected from any one or more ofthe elements in the list of elements, but not necessarily including atleast one of each and every element specifically listed within the listof elements and not excluding any combinations of elements in the listof elements. This definition also allows that elements may optionally bepresent other than the elements specifically identified within the listof elements to which the phrase “at least one” refers, whether relatedor unrelated to those elements specifically identified. Thus, as anon-limiting example, “at least one of A and B” (or, equivalently, “atleast one of A or B,” or, equivalently “at least one of A and/or B”) canrefer, in one embodiment, to at least one, optionally including morethan one, A, with no B present (and optionally including elements otherthan B); in another embodiment, to at least one, optionally includingmore than one, B, with no A present (and optionally including elementsother than A); in yet another embodiment, to at least one, optionallyincluding more than one, A, and at least one, optionally including morethan one, B (and optionally including other elements); etc.

In the claims, as well as in the specification above, all transitionalphrases such as “comprising,” “including,” “carrying,” “having,”“containing,” “involving,” “holding,” and the like are to be understoodto be open-ended, i.e., to mean including but not limited to. Only thetransitional phrases “consisting of” and “consisting essentially of”shall be closed or semi-closed transitional phrases, respectively, asset forth in the United States Patent Office Manual of Patent ExaminingProcedures, Section 2111.03.

The term “alkyl” refers to the radical of saturated aliphatic groups,including straight-chain alkyl groups, branched-chain alkyl groups,cycloalkyl (alicyclic) groups, alkyl substituted cycloalkyl groups, andcycloalkyl substituted alkyl groups. The alkyl groups may be optionallysubstituted, as described more fully below. Examples of alkyl groupsinclude, but are not limited to, methyl, ethyl, propyl, isopropyl,butyl, isobutyl, tert-butyl, 2-ethylhexyl, cyclopropyl, cyclobutyl,cyclopentyl, cyclohexyl, and the like. “Heteroalkyl” groups are alkylgroups wherein at least one atom is a heteroatom (e.g., oxygen, sulfur,nitrogen, phosphorus, etc.), with the remainder of the atoms beingcarbon atoms. Examples of heteroalkyl groups include, but are notlimited to, alkoxy, poly(ethylene glycol)-, alkyl-substituted amino,tetrahydrofuranyl, piperidinyl, morpholinyl, etc.

The terms “alkenyl” and “alkynyl” refer to unsaturated aliphatic groupsanalogous to the alkyl groups described above, but containing at leastone double or triple bond respectively. The “heteroalkenyl” and“heteroalkynyl” refer to alkenyl and alkynyl groups as described hereinin which one or more atoms is a heteroatom (e.g., oxygen, nitrogen,sulfur, and the like).

The term “aryl” refers to an aromatic carbocyclic group having a singlering (e.g., phenyl), multiple rings (e.g., biphenyl), or multiple fusedrings in which at least one is aromatic (e.g.,1,2,3,4-tetrahydronaphthyl, naphthyl, anthryl, or phenanthryl), alloptionally substituted. “Heteroaryl” groups are aryl groups wherein atleast one ring atom in the aromatic ring is a heteroatom, with theremainder of the ring atoms being carbon atoms. Examples of heteroarylgroups include furanyl, thienyl, pyridyl, pyrrolyl, N lower alkylpyrrolyl, pyridyl N oxide, pyrimidyl, pyrazinyl, imidazolyl, indolyl andthe like, all optionally substituted.

The terms “amine” and “amino” refer to both unsubstituted andsubstituted amines, e.g., a moiety that can be represented by thegeneral formula: N(R′)(R″)(R′″) wherein R′, R″, and R′″ eachindependently represent a group permitted by the rules of valence.

The terms “acyl,” “carboxyl group,” or “carbonyl group” are recognizedin the art and can include such moieties as can be represented by thegeneral formula:

wherein W is H, OH, O-alkyl, O-alkenyl, or a salt thereof. Where W isO-alkyl, the formula represents an “ester.” Where W is OH, the formularepresents a “carboxylic acid.” In general, where the oxygen atom of theabove formula is replaced by sulfur, the formula represents a“thiolcarbonyl” group. Where W is a S-alkyl, the formula represents a“thiolester.” Where W is SH, the formula represents a “thiolcarboxylicacid.” On the other hand, where W is alkyl, the above formula representsa “ketone” group. Where W is hydrogen, the above formula represents an“aldehyde” group.

As used herein, the term “heteroaromatic” or “heteroaryl” means amonocyclic or polycyclic heteroaromatic ring (or radical thereof)comprising carbon atom ring members and one or more heteroatom ringmembers (such as, for example, oxygen, sulfur or nitrogen). Typically,the heteroaromatic ring has from 5 to about 14 ring members in which atleast 1 ring member is a heteroatom selected from oxygen, sulfur, andnitrogen. In another embodiment, the heteroaromatic ring is a 5 or 6membered ring and may contain from 1 to about 4 heteroatoms. In anotherembodiment, the heteroaromatic ring system has a 7 to 14 ring membersand may contain from 1 to about 7 heteroatoms. Representativeheteroaryls include pyridyl, furyl, thienyl, pyrrolyl, oxazolyl,imidazolyl, indolizinyl, thiazolyl, isoxazolyl, pyrazolyl, isothiazolyl,pyridazinyl, pyrimidinyl, pyrazinyl, triazinyl, triazolyl, pyridinyl,thiadiazolyl, pyrazinyl, quinolyl, isoquinolyl, indazolyl, benzoxazolyl,benzofuryl, benzothiazolyl, indolizinyl, imidazopyridinyl, isothiazolyl,tetrazolyl, benzimidazolyl, benzoxazolyl, benzothiazolyl,benzothiadiazolyl, benzoxadiazolyl, carbazolyl, indolyl,tetrahydroindolyl, azaindolyl, imidazopyridyl, qunizaolinyl, purinyl,pyrrolo[2,3]pyrimidyl, pyrazolo[3,4]pyrimidyl, benzo(b)thienyl, and thelike. These heteroaryl groups may be optionally substituted with one ormore substituents.

The term “substituted” is contemplated to include all permissiblesubstituents of organic compounds, “permissible” being in the context ofthe chemical rules of valence known to those of ordinary skill in theart. In some cases, “substituted” may generally refer to replacement ofa hydrogen with a substituent as described herein. However,“substituted,” as used herein, does not encompass replacement and/oralteration of a key functional group by which a molecule is identified,e.g., such that the “substituted” functional group becomes, throughsubstitution, a different functional group. For example, a “substitutedphenyl” must still comprise the phenyl moiety and cannot be modified bysubstitution, in this definition, to become, e.g., a heteroaryl groupsuch as pyridine. In a broad aspect, the permissible substituentsinclude acyclic and cyclic, branched and unbranched, carbocyclic andheterocyclic, aromatic and nonaromatic substituents of organiccompounds. Illustrative substituents include, for example, thosedescribed herein. The permissible substituents can be one or more andthe same or different for appropriate organic compounds. For purposes ofthis disclosure, the heteroatoms such as nitrogen may have hydrogensubstituents and/or any permissible substituents of organic compoundsdescribed herein which satisfy the valencies of the heteroatoms. Thisdisclosure is not intended to be limited in any manner by thepermissible substituents of organic compounds.

Examples of substituents include, but are not limited to, alkyl, aryl,aralkyl, cyclic alkyl, heterocycloalkyl, hydroxy, alkoxy, aryloxy,perhaloalkoxy, aralkoxy, heteroaryl, heteroaryloxy, heteroarylalkyl,heteroaralkoxy, azido, amino, halogen, alkylthio, oxo, acyl, acylalkyl,carboxy esters, carboxyl, carboxamido, nitro, acyloxy, aminoalkyl,alkylaminoaryl, alkylaryl, alkylaminoalkyl, alkoxyaryl, arylamino,aralkylamino, alkylsulfonyl, carboxamidoalkylaryl, carboxamidoaryl,hydroxyalkyl, haloalkyl, alkylaminoalkylcarboxy, aminocarboxamidoalkyl,alkoxyalkyl, perhaloalkyl, arylalkyloxyalkyl, and the like.

What is claimed is:
 1. A system, comprising: a source of electromagneticradiation associated with a consumer electronic device; a sensorassociated with the consumer electronic device; an emissive specieswhich produces a detectable signal in the presence of electromagneticradiation produced by the source of electromagnetic radiation, thedetectable signal detectable by the sensor, the detectable signal havingone or more detectable delayed emissions having an emission time periodof greater than or equal to 10 nanoseconds; and an electronic hardwarecomponent associated with the consumer electronic device configured togenerate a single image, the single image comprising a first portion ofthe detectable signal corresponding to a first portion of the emissiontime period, and the single image comprising a second portion of thedetectable signal corresponding to a second portion of the emission timeperiod different than the first portion of the emission time period. 2.A system as in claim 1, wherein the detectable signal comprises one ormore delayed emissions of greater than or equal to 10 nanoseconds.
 3. Asystem as in claim 1, wherein the source of electromagnetic radiationcomprises an LED component.
 4. A system as in claim 1, furthercomprising a rolling shutter mechanism associated with the method.
 5. Asystem as in claim 1, wherein the emissive material absorbs lightemitted from a smartphone.
 6. A system as in claim 1, wherein theemissive material absorbs light at a wavelength of 440 nm or higher. 7.A system as in claim 1, wherein the detectable signal comprisessubtractive color, reflected color, chemiluminescence,prompt-fluorescence, delayed-fluorescence, prompt-phosphorescence, ordelayed-phosphorescence emission.
 8. A system as in claim 1, wherein theemissive material comprises a TADF emission.
 9. A system as in claim 1,wherein the emissive material comprises an organometallic compound. 10.A system as in claim 1, wherein the emissive material comprises ametallorganic material.
 11. A system as in claim 1, wherein the emissivematerial comprises Europium complex.
 12. A system as in claim 1, whereinthe emissive material comprises an organic molecule containing iodine orbromine atoms.
 13. A system as in claim 1, wherein the emissive materialis electronically coupled to or connected to a heavy atom.
 14. A systemas in claim 1, wherein the emissive material comprises metalloporphyrin.15. A system as in claim 1, wherein the emissive material is excited bya white light source.
 16. A system as in claim 1, wherein the emissivematerial is excited by an LED emitting between 440 and 700 nm.
 17. Amethod, comprising: using a consumer electronic device to determine anidentity or characteristic of a chemical/biological species, wherein theconsumer electronic device comprises a source of a spectrum ofelectromagnetic radiation; exposing an emissive species to the spectrumof electromagnetic radiation such that the emissive species produces adetectable delayed emission having an emission time period of greaterthan or equal to 10 nanoseconds which corresponds to the identity orcharacteristic of the chemical/biological species and which isdetectable by the consumer electronic device; and generating a singleimage, the single image comprising a first portion of the detectablesignal corresponding to a first portion of the emission time period, andthe single image comprising a second portion of the detectable signalcorresponding to a second portion of the emission time period differentthan the first portion of the emission time period.
 18. A method as inclaim 17, wherein one or more emissive species are excited and asmartphone detects a steady-state photon emission event and anon-steady-state emission event or optionally a non-steady-state photonemission event.
 19. A method as in claim 18, wherein a first portion ofthe electromagnetic radiation comprises a wavelength of between 425 nmand 475 nm and wherein a second portion of the electromagnetic radiationcomprises a wavelength of between 525 nm and 725 nm.
 20. A method as inclaim 17, wherein at least one emission is selected from the groupconsisting of subtractive color, reflected/scattered color,chemiluminescence, prompt-fluorescence, delayed-fluorescence,prompt-phosphorescence, or delayed-phosphorescence.